SKIN INFECTIONS









Acne

Pathology

  • Acne is caused by follicular hyperkeratinization, colonization with Propionibacterium acnes, sebum production, and complex inflammatory mechanisms. Acne affects 85% of people aged 12 to 25 years and it can persist, affecting up to 26% of women and 12% of men into their forties.

Treatment overview

  • There are few comparative studies in the treatment of acne; therefore, most recommendations are not evidence-based. The treatment algorithm presented here is derived from the AAP 2013 recommendations and the AAD 2016 guidelines.
  • Acne regimens typically require 6 - 12 weeks to achieve their full effect
  • If beneficial response to oral antibiotics is seen then continue for 3 - 4 months. Antibiotic use should be limited to prevent bacterial resistance.
  • Oral antibiotics should be prescribed with a retinoid +/- benzoyl peroxide. Oral antibiotic monotherapy is discouraged.
  • Upon stopping oral antibiotics, a 2.5% benzoyl peroxide cream washout for 2 weeks to eradicate resistant Propionibacterium acnes may be beneficial. Topical antibiotics may then be tried. If acne worsens, repeat course of oral antibiotics.
  • Postinflammatory hyperpigmentation from acne lesions typically resolves over a period of months. Sunscreen can help prevent further darkening. [1,2,27,30]

Treatment regimens

Mild acne (mainly small red spots and/or comedones)
Moderate acne (red inflamed lesions, back acne)
Severe acne (nodular, scarring)

Bites (animal and human)

Treatment overview

  • Rabies prophylaxis should be considered in appropriate cases
  • About 16% of dog bite wounds become infected
  • Purulent bite wounds are often polymicrobial (mixed aerobes and anaerobes). Nonpurulent wounds commonly yield staphylococci and streptococci.
  • Tetanus vaccine should be given to patients who have not had one within 10 years [3]

Treatment regimens

Animal bites (IDSA 2014)
Human bites (IDSA 2014)
Cat and dog bite prophylactic therapy (IDSA 2014)
  • Prophylactic therapy is recommended in the following patients:
    • Immunocompromised
    • Asplenic
    • Advanced liver disease
    • Preexisting or resultant edema of the affected area
    • Moderate to severe injuries, especially to the hand or face
    • Injuries that may have penetrated the periosteum or joint capsule
  • Therapy should be for 3 - 5 days

Boils and abscesses

Treatment

Boils and abscesses (IDSA 2014)
  • Simple (no systemic signs of infection, no cellulitis)
    • Incision and drainage only
    • Children with recurrent abscesses should be evaluated for neutrophil disorders [3]
  • Moderate (systemic signs of infection, cellulitis)
    • Incision and drainage
    • Empiric treatment with sulfamethoxazole-trimethoprim, doxycycline, or culture-guided treatment
    • Systemic signs of infection include fever, tachycardia, tachypnea, and elevated white count
    • Children with recurrent abscesses should be evaluated for neutrophil disorders [3]
Recurrent boils and abscesses (IDSA 2014)
  • Five day decolonization regimen that includes the following:
    • Intranasal mupirocin two times a day for 5 days each month
    • Daily chlorhexidine or dilute bleach (1/4 - 1/2 cup per full bath) washes
    • Daily washing of towels, sheets, clothes, combs, and razors
  • Other (regimen based on PMID 30763195)
    • Chlorhexidine 4% rinse-off for daily bathing and showering
    • Chlorhexidine 0.12% mouthwash twice daily
    • Intranasal mupirocin twice daily
    • NOTE: Regimen was performed for 5 days twice monthly over a period of 6 months

Studies

Clindamycin vs Sulfa/TMP vs Placebo for 10 days after I&D in patients with small abscesses, NEJM (2017) [PubMed abstract]
  • Design: Randomized, placebo-controlled trial (N=786 | length = 20 days) in patients with small skin abscesses (≤ 5 cm)
  • Treatment: Clindamycin 300 mg 3 times a day vs Sulfa/TMP 800/160 twice daily vs Placebo for 10 days
  • Primary outcome: clinical cure 7 to 10 days after the end of treatment
  • Results:
    • Primary outcome: Clindamycin - 83%, Bactrim - 82%, Placebo - 69% (p<0.001 for both vs placebo)
  • Findings: As compared with incision and drainage alone, clindamycin or TMP-SMX in conjunction with incision and drainage improves short-term outcomes in patients who have a simple abscess. This benefit must be weighed against the known side-effect profile of these antimicrobials.
Sulfa/TMP vs Placebo for 7 days after I&D in patients with abscesses, NEJM (2016) [PubMed abstract]
  • Design: Randomized, placebo-controlled trial (N=630 | length = 21 days) in patients > 12 years old with skin abscesses
  • Treatment: Four tablets of Sulfa/TMP 400/80 twice daily vs Placebo
  • Primary outcome: clinical cure of the abscess, assessed 7 to 14 days after the end of the treatment period
  • Results:
    • Primary outcome: Bactrim - 81%, Placebo - 74% (p=0.005)
  • Findings: In settings in which MRSA was prevalent, trimethoprim–sulfamethoxazole treatment resulted in a higher cure rate among patients with a drained cutaneous abscess than placebo

Cat scratch disease

Overview

  • Bartonella henselae causes most cat scratch disease
  • A papule or pustule develops from 3 - 30 days following a scratch or bite
  • Lymph nodes surrounding the inoculation enlarge about 3 weeks after the scratch
  • The benefit of antibiotics in cat scratch disease is questionable and mostly unproven
  • In most people, the disease resolves without treatment
  • Cutaneous bacillary angiomatosis may develop in immunocompromised patients [3,4]

Treatment (IDSA 2014)

Azithromycin
  • Patients > 45 kg: 500 mg on day 1 followed by 250 mg for 4 additional days ($)
  • Patients < 45 kg: 10 mg/kg on day 1 and 5 mg/kg for 4 more days ($)

Cellulitis (skin infection)

Treatment

Non-MRSA (IDSA 2014)
  • Pediatric
    • Cephalexin 25 - 50 mg/kg/day (max 2000 mg/day) given in 4 divided doses for 5 - 10 days ($)
    • Dicloxacillin 25 - 50 mg/kg/day (max 2000 mg/day) given in 4 divided doses for 5 - 10 days ($)
  • Adults
    • Cephalexin 500 mg four times a day for 5 - 10 days ($)
    • Dicloxacillin 500 mg four times a day for 5 - 10 days ($)
    • Penicillin VK 250 - 500 mg four times a day for 5 - 10 days (streptococcal infections only) ($)
MRSA coverage (IDSA 2014)
  • Pediatric
    • Clindamycin 30 - 40 mg/kg/day (max 1800 mg/day) given in 3 divided doses for 5 - 10 days ($$-$$$)
    • Linezolid 10 mg/kg/dose given twice a day for 5 - 10 days ($$)
    • Sulfamethoxazole-trimethoprim 8 – 12 mg/kg/day (based on trimethoprim component) given in 2 divided doses for 5 - 10 days ($)
MRSA coverage (other)
  • Adults
    • Omadacycline 450 mg once daily for 2 days followed by 300 mg once daily for a total of 7 - 14 days ($$$$)

Studies

Compression Stockings vs Education to Prevent Recurrent Cellulitis, NEJM (2020) [PubMed abstract]
  • Design: Randomized controlled trial (N=84 | length = median 186 days) in patients with ≥ 2 episodes of cellulitis in the same leg within the previous 2 years along with ≥ 3 months of leg edema
  • Treatment: Compression stockings + Education vs Education alone
  • Primary outcome: Recurrence of cellulitis
  • Results:
    • Primary outcome: Compression stockings - 15%, Education alone - 40% (p=0.002)
  • Findings: In this small, single-center, nonblinded trial involving patients with chronic edema of the leg and cellulitis, compression therapy resulted in a lower incidence of recurrence of cellulitis than conservative treatment.
Cephalexin + Sulfa/TMP vs Cephalexin alone for Uncomplicated Cellulitis , JAMA (2017) [PubMed abstract]
  • Design: Randomized, placebo-controlled trial (N=500 | length = 21 days) in outpatients older than 12 years with cellulitis and no wound
  • Treatment: Cephalexin 500 mg 4 times a day + Sulfa/TMP 320/1600 twice daily vs Cephalexin only for 7 days
  • Primary outcome: Clinical cure, defined as absence of these clinical failure criteria at follow-up visits: fever; increase in erythema (>25%), swelling, or tenderness (days 3-4); no decrease in erythema, swelling, or tenderness (days 8-10); and more than minimal erythema, swelling, or tenderness (days 14-21)
  • Results:
    • Primary outcome: Ceph + Sulfa/TMP - 83.5%, Ceph only - 85.5% (p=0.50)
  • Findings: Among patients with uncomplicated cellulitis, the use of cephalexin plus trimethoprim-sulfamethoxazole compared to cephalexin alone did not result in higher rates of clinical resolution of cellulitis in the per-protocol analysis. However, because imprecision around the findings in the modified intention-to-treat analysis included a clinically important difference favoring cephalexin plus trimethoprim-sulfamethoxazole, further research may be needed.
Clindamycin vs Sulfa/TMP for Uncomplicated Cellulitis, NEJM (2015) [PubMed abstract]
  • Design: Randomized, controlled trial (N=524 | length = 20 days) in outpatients with uncomplicated skin infections who had cellulitis, abscesses larger than 5 cm in diameter (smaller for younger children), or both
  • Treatment: Clindamycin 300 mg 3 times a day vs Sulfa/TMP 800/160 mg twice daily for 10 days
  • Primary outcome: clinical cure 7 to 10 days after the end of treatment
  • Results:
    • Primary outcome: Clindamycin - 80%, Sulfa/TMP - 78% (p=0.52)
    • MRSA status did not affect cure rates.
  • Findings: We found no significant difference between clindamycin and TMP-SMX, with respect to either efficacy or side-effect profile, for the treatment of uncomplicated skin infections, including both cellulitis and abscesses

Diabetic foot ulcer

Treatment overview

  • Only infected wounds should be cultured. Cultures should be from deep tissue after debridement and not from swab specimens.
  • Uninfected wounds should not be treated with antibiotics
  • All patients should have a foot X-ray. MRI may be necessary in patients where abscess or osteomyelitis is suspected.
  • Wounds should be debrided, and pressure should be off-loaded from the wound
  • Skin equivalents, growth factors, granulocyte colony-stimulating factors, hyperbaric oxygen therapy, and negative pressure wound therapy have not been proven to improve wound healing [5]

Treatment (IDSA 2014)

Diabetic foot ulcer, empiric treatment for mild infections
  • NOTE: IDSA makes no specific dosing recommendations. Dosing presented here based on PI and/or IDSA cellulitis recs.
Diabetic foot ulcer, empiric treatment for moderate infections
  • NOTE: IDSA makes no specific dosing recommendations. Dosing presented here based on PI and/or IDSA cellulitis recs
    • Non-MRSA
    • MRSA coverage
      • Linezolid 400 - 600 mg twice daily for 7 - 14 days ($$)
Clindamycin was not listed under MRSA coverage, but it was noted to be "Usually active against community-associated MRSA"

Herpes labialis | Fever blisters | Cold sores

Overview

  • Initiate therapy at the first sign of fever blister (tingling, burning, itching)
  • Antivirals decrease healing time and speed resolution by about 1 - 2 days on average [32]

Treatment

Acute episode
Suppressive therapy
Topical treatment
  • Acyclovir cream - apply 5 times a day for 4 days. Approved for ≥ 12 years. Indicated for recurrent episodes. ($$$$)
  • Xerese cream - apply 5 times a day for 5 days. Approved for ≥ 6 years. Indicated for recurrent episodes. ($$$$)

Herpes zoster | Varicella zoster | Shingles

Epidemiology

  • Herpes zoster is caused by varicella zoster virus (VZV). VZV infection typically occurs in childhood (chickenpox), and it's estimated that 95% of the world's population has been infected.
  • For patients infected with varicella, the lifetime risk of shingles is 10 - 20%. For patients who live to be 85 years, the lifetime risk is 50%.

Symptoms

  • Herpes zoster typically starts with pain, itching, and/or tingling in an area of skin on one side of the body. Over the course of 1 - 3 days, a blistering rash appears. The rash is typically confined to an area of skin that a single nerve innervates (dermatome) on one side of the body. Fever, headache, malaise, and lymphadenopathy are common. The blisters eventually become pustular and crust over (herpes zoster images).
  • The chest, neck, forehead, and lumbosacral areas are most commonly affected. In most cases, the condition resolves in 2 - 4 weeks. Postherpetic neuralgia (pain that persists for ≥ 90 days after the onset of rash) occurs in 10 - 50% of patients.

Shingles vaccine

  • There are two shingles vaccines - Shingrix and Zostavax. Shingrix cuts the risk of shingles by roughly 90% for at least 4 years. Zostavax cuts the risk by about 50%. The vaccines also reduce the risk of postherpetic neuralgia should shingles occur. Shingrix is a dead vaccine and Zostavax is a live vaccine. [13,14,28]
  • Shingrix is preferred over Zostavax, and it is recommended for all adults ≥ 50 years. See screening and immunization recommendations for more

Treatment overview

  • Postherpetic neuralgia (PHN) is defined as pain persisting for ≥ 90 days after onset of rash. PHN develops in 10 - 50% of patients with herpes zoster (risk increases with age).
  • Antivirals decrease pain and speed resolution of rash, but have not been proven to decrease risk of PHN
  • Steroids may benefit acute pain. They have not been proven to reduce the risk of PHN.
  • Most zoster trials have excluded patients with symptoms > 72 hours, but this does not mean treatments do not benefit patients with symptoms > 72 hours
  • Patients with visual symptoms should be referred to ophthalmology
  • The lifetime risk of recurrent shingles in immunocompetent individuals is 5%

Treatment regimens (IDSA 2007)

Antivirals - most patients
  • Acyclovir 800 mg five times a day for 7 - 10 days ($)
  • Famciclovir 500 mg three times a day for 7 days ($-$$)
  • Valacyclovir 1000 mg three times a day for 7 days ($)
Corticosteroids - select patients
  • Prednisone 60 mg a day for 7 days, then 30 mg a day for 7 days, then 15 mg a day for 7 days, then discontinue (IDSA regimen, others may suffice) ($)
Pain control

Hidradenitis suppurativa

Overview

  • Hidradenitis suppurativa (HS) is a skin condition that is marked by recurrent painful, pruritic nodules in the apocrine-gland regions that progress to chronic purulent discharge, scarring, and sinus formation. The axillary (armpits) and inguinal (groin) areas are most commonly affected (hidradenitis suppurativa images).
  • The pathology of HS involves perifollicular lymphocyte infiltration of the hair follicles followed by sebaceous gland loss. As HS progresses, local increases in interleukin (IL)-1, tumor necrosis factor (TNF), IL-17, S100A8 protein, S100A9 protein, caspase-1, and IL-10 lead to the migration of neutrophils, monocytes, and mast cells into the affected tissue. Chronic inflammation causes tissue destruction and scarring.
  • Risk factors include female sex, smoking, family history, and obesity
  • No consensus guidelines for HS treatment have been published [16,17,29]

Treatment


Impetigo

Overview

  • Impetigo is a common bacterial infection of the superficial skin caused by Staphylococcus aureus and β-hemolytic Streptococcus (Strep pyogenes). Impetigo appears acutely and is marked by pustules and golden-crusted erosions (impetigo images).
  • Impetigo may be treated with topical and/or oral antibiotics. Oral antibiotics are recommended for patients with numerous lesions. If MRSA is suspected, doxycycline, clindamycin, or sulfamethoxazole-trimethoprim (SMX-TMP) should be used (see cellulitis for more).

Treatment regimens

Pediatric (IDSA 2014)
  • Amoxicillin-clavulanate 25 mg/kg/day (max 1750 mg/day) of the amoxicillin component given in 2 divided doses for 7 days ($)
  • Cephalexin 25 - 50 mg/kg/day (max 1000 mg/day) given in 3–4 divided doses for 7 days ($)
  • Clindamycin 20 mg/kg/day (max 1600 mg/day) given in 3 divided doses for 7 days ($-$$)
  • Erythromycin 40 mg/kg/day (max 1000 mg/day) given in 3–4 divided doses for 7 days ($$$$)
  • Mupirocin - apply ointment twice a day for 5 days ($)
  • Retapamulin - apply ointment twice a day for 5 days ($$$-$$$$)
Pediatric (other)
  • Benzathine penicillin G (Bicillin L-A®)
    • ≤ 6 kg: 225 mg (300,000 units) IM given as a one time dose
    • 6.1 - 10 kg: 337.5 mg (450,000 units) IM given as a one time dose
    • 10.1 - 15 kg: 450 mg (600,000 units) IM given as a one time dose
    • 15.1 - 20 kg: 675 mg (900,000 units) IM given as a one time dose
    • > 20 kg: 900 mg (1,200,000 units) IM given as a one time dose ($$-$$$)
  • Sulfamethoxazole-trimethoprim
    • Once daily: 8 mg/kg/day (trimethoprim component) (max 320 mg/day) given once daily for 5 days
    • Twice daily: 8 mg/kg/day (trimethoprim component) (max 320 mg/day) given in two divided doses for 3 days ($)
Adults (IDSA 2014)

Lice

Disease overview

  • Most common symptom is itching. Itching may not develop for 4 - 6 weeks after first infestation.
  • Adult louse is about the size of a sesame seed and is usually tan to grayish-white in color
  • Diagnosis is made by observation of louse or eggs. Lice are commonly found behind the ears and on the back of the neck. Eggs are found 1 cm from the scalp and are pigmented to match the color of the hair. Empty egg casings called "nits" are white and can be found throughout the hair. Nits may remain in the hair for months after successful treatment.
  • Lice are typically passed through direct contact. Passage through contaminated fomites is uncommon.
  • CDC website with information on lice

Treatment overview

  • Presence of nits (empty louse eggs) does not indicate active infection. Nits are often confused with dandruff and other debris. Nits and eggs are firmly affixed to the hair shaft where dandruff is not.
  • Children with head lice should not be kept out of school, because lice do not pass easily within classrooms
  • Family members of infested patients should be examined and treated if live lice are found
  • Lice typically survive for less than a day away from the scalp. Only items that have been in contact with the head of the infected person in the 24 - 48 hours before treatment should be considered for cleaning. Washing or drying items at ≥ 130° F should be sufficient. Furniture and carpeting can be vacuumed.
  • Treatment of pubic lice is similar to head lice [12, 21]

Topical treatment

Over-the-counter (OTC)
  • Permethrin 1% lotion (Nix®) - apply to damp hair and scalp. Leave on for 10 minutes then rinse with water. Repeat in 7 days if necessary. Approved for patients ≥ 2 months. ($)
  • Pyrethrins 0.3% / piperonyl butoxide 4% shampoo (Rid®) - apply to dry hair and scalp. Leave on for 10 minutes then wash with water and shampoo. Repeat in 7 - 10 days. Approved for patients ≥ 2 years. ($)
Prescription
  • Benzyl alcohol 5% lotion (Ulesfia®) - apply to dry hair to completely saturate the scalp and hair; leave on for 10 minutes, then thoroughly rinse off with water. Repeat application after 7 days. The Ulesfia® PI gives recommendations for the number of bottles needed depending on hair length - Ulesfia® PI. Approved for children ≥ 6 months. ($$-$$$$)
  • Malathion 0.5% lotion (Ovide®) - apply lotion on dry hair in amount just sufficient to thoroughly wet the hair and scalp. Allow hair to dry naturally. After 8 - 12 hours, shampoo hair. Rinse and use fine tooth comb. Repeat in 7 - 9 days if necessary. Not approved for infants. ($$-$$$)
  • Spinosad 0.9% (Natroba®) - apply to dry scalp and hair. Leave on for 10 minutes then rinse with warm water. May repeat in 7 days. Approved for patients ≥ 4 years. ($$$-$$$$)
  • Ivermectin lotion (Sklice®) - apply to dry hair and scalp. Leave on for 10 minutes then rinse with water. Approved for patients ≥ 6 months. ($$$$)

Systemic treatment


Onychomycosis (nail fungus)

Overview

  • Onychomycosis is typically caused by Trichophyton species
  • Nail findings include subungual hyperkeratosis (excessive proliferation and scaling of the skin under the nail), onycholysis (detachment of nail plate from its bed), nail thickening and crumbling, and yellow and/or white discoloration. Tinea pedis is also present in up to a third of patients.
  • Onychomycosis is the most common cause of nail dystrophies, but other etiologies are present in 50% of patients; therefore, the diagnosis should be confirmed before treatment. [26]

Diagnostic testing

  • PAS staining - sensitivity 82%
  • KOH stain of nail scraping - sensitivity 48%
  • Fungal culture - sensitivity 53% [25]

Treatment success

  • Topical treatments should be reserved for cases where < 50% of the nail is involved, ≤ 4 nails affected, and nail thickness < 3 mm [26]
  • Full effect of treatment not seen for > 12 months [26]
  • Relapse occurs in about 25 - 30% of patients [9]

  • Mycological cure - negative culture and negative KOH
  • Normal nail - mycological cure and completely normal-appearing nail
  • Reference - Manufacturer PI
Treatment Mycological cure Normal nail
Terbinafine 70% 38%
Itraconazole 54% 14%
Ciclopirox 36% 9%
Efinaconazole 55% 18%
Tavaborole 31% 7%

Treatment regimens

Systemic (oral) therapy
  • Toenails
    • Terbinafine (Lamisil®) 250 mg once daily for 12 weeks ($)
    • Itraconazole (Sporanox®) 200 mg once daily for 12 weeks; OR 200 mg twice daily for 1 week a month for 3 consecutive months ($$$$)
    • Griseofulvin
      • Griseofulvin microsize 500 mg once daily for 6 months ($$$$)
      • Griseofulvin ultramicrosize 375 mg twice daily for 6 months ($$$$)
  • Fingernails
Topical
  • Ciclopirox 8% (Penlac®) - Apply once daily at bedtime to affected nail(s) for 48 weeks. Cover entire nail and under the tip. FDA-approved for toenails and fingernails. One 6.6 ml bottle ($)
  • Efinaconazole 10% (Jublia®) - Apply once daily to affected nail(s) for 48 weeks. When applying, ensure that the toenail, the toenail folds, toenail bed, hyponychium, and the undersurface of the toenail plate, are completely covered. FDA-approved for toenails only. ($$$$)
  • Tavaborole 5% (Kerydin®) - Apply once daily to affected nail(s) for 48 weeks. Cover entire nail and under the tip. FDA-approved for toenails only. ($$$$)

Pseudofolliculitis barbae

Overview

  • Pseudofolliculitis barbae (PB) develops after shaving when cut hairs curl inwards back into the skin. The ingrown hair produces an inflammatory reaction that may lead to infection, scarring, hyperpigmentation, and keloids.
  • Predominantly seen in patients of African descent
  • The face, axilla, and pubic areas are most commonly affected
  • Acne keloidalis nuchae is a related condition that occurs on the occipital scalp (back of the head)
  • No consensus treatment recommendations have been published [19]
  • Randomized trials of PB treatments are almost nonexistent

Treatment (mostly unvalidated in clinical trials)


Scabies

Disease overview

  • Scabies is caused by the mite, Sarcoptes scabiei variety hominis. Scabies affects > 300 million people annually.
  • Scabies is typically passed through direct skin-to-skin contact. Passage through fomites (linens, clothing) is uncommon.
  • Symptoms typically develop within 2 - 6 weeks after infection and include generalized itching that is worse at night, red papules at sites of infection, and wavy lines where the mite burrows.
  • Lesions are typically found on the interdigital finger webs and flexor surfaces of the wrists. Elbows, armpits, buttocks, and genitalia are also involved, as are the breast areola in women. Infants can develop lesions over the entire body (scabies images).
  • Skin scrapings have very low diagnostic sensitivity
  • CDC website with information on scabies

Treatment overview

  • Bed linen and clothing should be washed in hot water. Shoes and other nonwashable items should be sealed in an airtight plastic bag for 3 days.
  • In the first few days after initiating therapy, itching may worsen and/or persist. This is not a sign of treatment failure.
  • One treatment is generally sufficient. Need for repeat treatment is rare.
  • Close contacts of infected individuals may need to be treated [10,11,31]

Treatment regimens

First-line
  • Permethrin 5% cream (Elimite®) - thoroughly massage cream into the skin from the head to the soles of the feet. Leave on for 8 - 14 hours (preferably overnight), then wash. Infants should be treated on the scalp, temple, and forehead. May repeat in 8 - 15 days if necessary. ($)
Other
  • Sulfur ointment 5 - 10% - In studies, has been applied for 3 days to 3 weeks. Ointment is applied over entire body, washed off after 24 hours, and then reapplied for another 24 hours. Available OTC in a number of products. [PMID 29018829, PMID 26342502, PMID 27027929]
  • Ivermectin (Stromectol®) 200 mcg/kg/dose given one time and then repeated in 8 - 15 days (NOTE: 1000 mcg = 1 mg). Take with food. ($)

NOTE: Ivermectin is approved for patients ≥ 5 years but has been used in trials in patients ≥ 2 years who weigh at least 15 kg (see lice above)
Body weight (kg) Number of 3 mg ivermectin tablets
15 - 24 1
25 - 35 2
36 - 50 3
51 - 65 4
66 - 79 5
≥ 80 200 mcg/kg


Tinea capitis (scalp fungus)

Disease overview

  • Tinea capitis is a fungal infection of the scalp. Symptoms of tinea capitis include flaking, broken-off hairs, alopecia, occipital lymphadenopathy, pustules and kerions, and circular grey patches (tinea capitis images).
  • In the U.S., 90 percent of cases are caused by Trichophyton tonsurans, and fewer than 5 percent are caused by Microsporum species

Treatment overview

  • Topical treatments are not effective against tinea capitis
  • Terbinafine is not effective against Microsporum species
  • Griseofulvin and azoles are effective against Microsporum species
  • Combs and brushes should be sterilized
  • Lab monitoring (CBC, ALT, AST) during griseofulvin treatment does not appear to be necessary in healthy patients
  • Lab monitoring during terbinafine therapy (CBC, AST, ALT) of < 6 weeks duration is likely unnecessary in healthy patients [6,7,22]

Treatment

Pediatric (Infants)
Pediatric (≥ 1 year)
  • Terbinafine tablets
  • NOTE: Tablet dosing based on one small study [PMID 12195561]
    • Weight 10 - 20 kg: 62.5 mg daily for 4 weeks
    • Weight 20 - 40 kg: 125 mg daily for 4 weeks
    • Weight > 40 kg: 250 mg daily for 4 weeks ($)
  • Terbinafine granules
  • NOTE: Terbinafine granules are FDA-approved for children ≥ 4 years old
    • Weight < 25 kg: 125 mg daily for 6 weeks
    • Weight 25 - 35 kg: 187.5 mg daily for 6 weeks
    • Weight > 35 kg: 250 mg daily for 6 weeks
  • Griseofulvin microsize
    • 20 - 25 mg/kg once daily for 6 - 8 weeks ($-$$$)
  • Griseofulvin ultramicrosize
    • 10 - 15 mg/kg once daily for 6 - 8 weeks ($$-$$$$)
  • Itraconazole
    • 5 mg/kg once daily for 2 - 4 weeks ($$$$)
    • Alternative:
      • Weight < 20 kg: 50 mg once daily for 4 weeks
      • Weight > 20 kg: 100 mg once daily for 4 weeks
      • [Based on PMID 11069511]
  • Fluconazole
    • 6 mg/kg once daily for 2 - 3 weeks ($-$$)
    • [Based on PMID 10468805]
    • Alternative:
      • 8 mg/kg once weekly for 8 - 12 weeks ($-$$)
      • [Based on PMID 10809856]
Adults

Tinea corporis (ringworm)

Overview

  • Tinea corporis is a fungal infection of the skin that is commonly caused by Trichophyton species. The rash in tinea corporis is pruritic and erythematous with a scaly, raised edge that may contain pustules or vesicles. It spreads centrifugally and results in annular patches of varying sizes (tinea corporis images).
  • When lesions are confined to a small area, topical medications are preferred [7,8]

Treatment

Pediatric
  • First-line
    • Terbinafine (Lamisil®) topical - topical terbinafine 1% applied once or twice daily ($)
    • Topical azoles (e.g. clotrimazole, miconazole) - apply twice daily ($)
  • Extensive and/or resistant cases
    • Terbinafine tablets
    • NOTE: Dosing based on study in children ≥ 2 years with tinea capitis [PMID 12195561]
      • Weight 10 - 20 kg: 62.5 mg daily for 2 - 4 weeks
      • Weight 20 - 40 kg: 125 mg daily for 2 - 4 weeks
      • Weight > 40 kg: 250 mg daily for 2 - 4 weeks ($)
    • Fluconazole (Diflucan®) 6 mg/kg (max 150 mg) once weekly for 2 - 4 weeks ($)
    • Griseofulvin
      • Griseofulvin microsize 10 mg/kg once daily (max 500 mg/day) for 2 - 4 weeks ($-$$)
      • Griseofulvin ultramicrosize 7.25 mg/kg once daily (max 375 mg/day) for 2 - 4 weeks ($$$-$$$$)
Adults

Tinea cruris (jock itch) | Tinea pedis (athlete's foot) | Tinea manuum (hand infection)

Tinea cruris and pedis

  • Tinea cruris is a fungal infection of the groin and tinea pedis is a fungal infection of the foot. They are commonly caused by Trichophyton species. The rash is pruritic and erythematous with a scaly, raised edge that may contain pustules or vesicles. The rash spreads centrifugally and results in annular patches of varying sizes. Interdigital tinea pedis can appear as macerated red erosions (tinea pedis images).
  • Tinea cruris and tinea pedis often occur together. Both should be treated or recurrence is likely.
  • Talc powders (e.g. Gold Bond®) absorb moisture and may help prevent recurrences
  • Patients should be instructed to avoid tight-fitting clothes and to keep feet dry [7,8]

Tinea manuum

  • Tinea manuum is a fungal infection of the hand commonly caused by Trichophyton species. Tinea manuum is typically unilateral and presents as a dry, scaly rash covering the palms (tinea manuum images). [7]

Treatment

Pediatric
  • First-line
    • Terbinafine (Lamisil®) topical - topical terbinafine 1% applied once or twice daily ($)
    • Topical azole (e.g. clotrimazole, miconazole) - apply twice daily ($)
  • Extensive and/or resistant cases
    • Terbinafine tablets
    • NOTE: Dosing based on study in children ≥ 2 years with tinea capitis [PMID 12195561]
      • Weight 10 - 20 kg: 62.5 mg daily for 2 - 4 weeks
      • Weight 20 - 40 kg: 125 mg daily for 2 - 4 weeks
      • Weight > 40 kg: 250 mg daily for 2 - 4 weeks ($)
    • Fluconazole (Diflucan®) 6 mg/kg (max 150 mg) once weekly for 2 - 4 weeks ($)
    • Griseofulvin
      • Griseofulvin microsize 10 mg/kg once daily (max 500 mg/day) for 2 - 8 weeks ($-$$)
      • Griseofulvin ultramicrosize 7.25 mg/kg once daily (max 375 mg/day) for 2 - 8 weeks ($$$-$$$$)
Adults

Tinea versicolor (pityriasis versicolor)

Overview

  • Tinea versicolor is a fungal infection of the skin caused by Malassezia yeast species. The rash is marked by irregularly shaped, scaly patches of hypo- or hyperpigmented skin. The back (most common), chest, neck, and face are typically affected (tinea versicolor images).
  • Recurrence after treatment is common (80% at 2 years) [8]
  • Topical terbinafine (Lamisil®) is effective, but oral terbinafine is not [23]

Treatment

Topical
  • Selenium sulfide 2.5% lotion - apply to affected area and lather with a small amount of water. Leave on skin for 10 minutes then rinse off. Perform once daily for 7 days, then on the first and third day of the month for 6 months (2.5% strength is prescription-only) ($)
  • Ketoconazole 2% shampoo (Nizoral®) - Apply the shampoo to the damp skin of the affected area and a wide margin surrounding this area. Lather, leave in place for 5 minutes, and then rinse off with water. Perform once daily for up to 3 days. (2% strength is prescription-only) ($)
  • Zinc pyrithione shampoo (Head and Shoulders®, etc.) - Apply to affected area and leave in place for 5 minutes. Perform daily for 2 weeks. ($)
  • Terbinafine (Lamisil®) - topical terbinafine applied twice daily for one week ($) NOTE: Oral terbinafine is not effective [23]
Systemic (oral) therapy



Pricing legend
  • $ = 0 - $50
  • $$ = $51 - $100
  • $$$ = $101 - $150
  • $$$$ = > $151
  • Pricing based on one month of therapy at standard dosing in an adult
  • Pricing based on information from GoodRX.com®
  • Pricing may vary by region and availability