Tinea Pedis Infection - Guidelines for Prescribing Topical Antifungals

Description of tinea pedis infections (athlete’s foot)
  • Fungal or tinea infections of the skin are common. Tinea pedis (athlete’s foot) has an incidence of up to 50% of the general population. More common in men and teenagers. Children under 12 years of age rarely develop the condition.
  • Superficial fungal infections of the skin are caused by three dermatophytes; Trichophyton, Epidermophyton and Microsporum, which use the keratin layer of the epidermis as their source of nutrition.
  • The type of tinea infection is classified by where it is located on the body, not by the causative organism.
  • Tinea infections are contagious. Athlete's foot can be spread from person to person through contaminated towels, clothing or surfaces. Tinea dermatophytes proliferate in warm and humid places such as showers, swimming pools and changing rooms.
  • Athlete’s foot occurs most commonly between the toes and may spread to the instep or sole. The skin may be cracked or scaly with blisters, inflammation and an itching or burning sensation. It may also cover the soles of the feet and involve the toenails. This is called moccasin-type infection.
  • Tinea pedis is often the cause of tinea cruris or corporis from self-inoculation (touching affected feet to other areas of the body or scratching feet and not washing hands).
  • Risk factors for developing:
    • Direct contact with infected persons, animals, fomites
    • Conditions of increased moisture
    • Genetic susceptibility
    • Impaired immunity (diabetes, HIV, chemo)
    • Going barefoot in public areas (eg. change rooms)
For more information and photos, go to:
Skinsight.com
DermNet NZ
Signs and Symptoms

Athlete’s foot occurs most commonly between the toes and may spread to the instep or sole. May be inflamed, blistered and feel itchy, burning or painful.

Classification

  • Interdigital infection, the most common form
    • White, cracked, macerated areas between the toe
    • Untreated interdigital infection may progress to moccasin-type tinea pedis
  • Moccasin-type infection
    • Usually present on the soles of both feet and may progress to sides and top of foot
    • Diffuse inflammation and scaling
    • Often affects the toenails
  • Vesiculobullous type infection
    • Blistering on the instep and middle of the bottom of the arch           
    • More often seen in summer
Differential Assessment

Rule out the following conditions which can resemble tinea pedis:

  • Allergic contact dermatitis - itchy rash caused by reaction to materials in stockings or shoes (e.g. latex). Refer to Guideline for Atopic Dermatitis.
  • Candidiasis - yeast infection between the toes - moist, white peeling skin. This can be treated with OTC antifungals.
  • Seborrheic dermatitis - appears as yellow, greasy, scales on scalp and may extend down to face and upper chest in the form of circular scaly pink patches. In some cases can also affect areas between the toes. May respond to self-care treatment. More severe cases should be referred to a physician.
  • Plantar keratosis – discrete, focused callus that typically appears in weight-bearing parts of the foot (heel or ball).  Non-pharmacologic measures are the mainstay of treatment (emollients, orthotics for shoes, pumice stones).
  • Psoriasis - presents as red spots covered with thick silver scales. Refer to physician.
  • Erythrasma - a bacterial infection causing slowly enlarging areas of pink or brown scaling skin in folds in the groin, armpits or between the toes. Often asymptomatic. Treated with topical or systemic antibiotics. Refer to physician.
  • Bacterial infections which occur when there is damage to the skin such as scrapes or cuts. Refer to Guideline for Bacterial Skin Infections.

 

When to Refer

Most patients with tinea pedis (athlete's foot) signs and symptoms do not require further investigation, however a physician assessment should be recommended if:

  • If the lesions are:
      • Extensive (eg. both top and bottom of feet affected).
      • Severely inflamed
      • Weeping or purulent
      • Painful
      • Disabling
  • No improvement after 1 week of pharmacologic treatment.  Refer for an evaluation.
  • Previous tinea infection which did not fully resolve, despite appropriate treatment. Refer for evaluation and possible systemic treatment.
  • Patient has diabetes or is immunocompromised due to disease or drug treatment.
  • Patient has symptoms of systemic illness (e.g. fever, fatigue, swollen lymph glands).
  • Unable to confirm patient self-diagnosis of tinea pedis - requires further evaluation and /or physician-supervised treatment (see Differential Diagnosis above).
  • Onychomycosis (fungal nail infection) is present:
    • Untreated athlete’s foot may spread to toenails.
    • Fingernails weakened by prolonged submersion in water may become infected with tinea and also with candidal infections.
    • Onychomycosis does not respond to topical treatment and must be treated with oral agents that can penetrate the infection site.
    • Suspected nail fungal infection should be referred to a physician for oral anti-fungal treatment.
  •  
Treatment

1. Non-pharmacological treatment for tinea infections:

  • Skin should be kept dry to help stop infection from spreading.
  • Avoid rubbing or scratching lesions.
  • Use a hair dryer on cool setting to dry the affected area.
  • Wear cotton socks.
  • Wear footwear that keeps the feet cool and dry.
  • Avoid going barefoot in public places.
  • Avoid scratching affect skin to prevent spreading.
  • Launder items used by infected person separately and often.
  • Use of non-medicated powders may help absorb moisture.  Do not use cornstarch or powders that contain cornstarch as these may provide nourishment for the tinea organisms

2. Over-the-counter drug options for treating tinea infections of the skin

  • OTC anti-fungal agents are often available in a variety of dosage forms; creams, lotions, gels, solutions, sprays and powders.  Generally creams and solutions are most effective because they can be massaged into infected areas so more of the product comes in contact with the fungus. Solutions may be easier to apply to hairy areas. Sprays and powders can be useful as adjunctive treatment, especially for oozing lesions and as preventative agents.
    • Tolnaftate 1% available in solution, gel, powder, cream, spray
    • Clotrimazole 1% available in cream
    • Miconazole 2% available in cream, powder spray
  • Directions for application of creams and solutions should include instructions to clean and dry the area and to apply product to visible lesions as well as 2cm to 5cm outside the visible infection. This will help treat fungus which is in the process of spreading. Massage creams into area twice a day for at least 4 weeks. Products should continue to be used for 1 week following resolution to help prevent recurrent infection. Apply sprays and powders to dry footwear as well as to skin.
  • OTC anti-fungal treatments have been shown to be effective in treating and curing tinea infections of the skin, but they may require longer duration of treatment than with prescription agents.
  • Clotrimazole and miconazole are the agents of choice in pregnancy.
  • In breastfeeding patients, clotrimazole is the drug of choice, but miconazole is acceptable.
  • Tolnaftate has not been thoroughly studied in pregnancy and lactation.

3.  Prescription drug options

Terbinafine 1% Cream and Terbinafine 1% Spray

    • Terbinafine has a broad spectrum of anti-fungal activity. It is fungicidal to dermatophytes by interfering with fungal sterol biosynthesis.
    • Terbinafine has a slightly higher cure rate than other topical treatments.
    • Dosage: Children > 12 years old and Adults:  Apply to clean, dry affected area and surrounding area (approximately 2cm beyond visible edge of lesions) and apply ONCE daily for 7 days. Patients may continue to improve for up to 4 weeks after treatment.
    • Less than 5% is absorbed after topical application. Half-life is 27 hours in the stratum corneum.
    • Pregnancy: There are only limited clinical studies so current recommendations are to avoid during pregnancy. However it is not expected to increase the risk of birth defects. Clotrimazole and miconazole are the agents of choice in pregnancy.
    • Lactation: With topically applied cream and spray treatment, the small amounts absorbed through the skin are unlikely to affect the infant.
    • Pediatrics: Topical terbinafine has not been studied in children <12, so should not be recommended

Ketoconazole 2% Cream

    • Ketoconazole is fungicidal to tinea dermatophytes by interfering with fungal sterol biosynthesis.
    • Dosage: Apply to clean, dry affected area and surrounding area (approximately 2cm beyond visible edge of lesions) ONCE daily. Duration of treatment 4 to 6 weeks.
    • Systemic absorption is minimal to undetectable.
    • Treatment should meet, but not exceed recommended duration as safety for longer periods has not been established.
    • Pregnancy: Adverse effects are noted in animal studies with oral ketoconazole. Systemic absorption is very low suggesting that ketoconazole is unlikely to have adverse effects but there is no data to confirm safety. The official recommendation is to avoid during pregnancy. Clotrimazole and miconazole are the agents of choice in pregnancy.
    • Lactation: Has been detected in breast milk at very low concentrations, but since it requires acidic conditions for absorption from the GI tract and alkaline conditions are induced by milk ingestion, significant absorption by breast feeding is unlikely. Rated as probably safe in breastfeeding by the American Academy of Pediatrics.
    • Pediatrics: Can be used in infants and children

Steroid or combination steroid/anti-fungal products should not be recommended. The itch caused by tinea infections subsides fairly soon after topical antifungal treatment begins. Extended treatment with these products may unnecessarily expose patients to steroid side effects.

 Nystatin is ineffective.

General Advice / Monitoring
  • Discuss and recommend appropriate non-pharmacologic measures.
  • Improvement of symptoms such as itching and burning should occur within a few days, and the infection is not contagious after 24 hours of treatment.
    • Although a person should no longer be contagious 24 hours following the initiation of treatment, the patient should be instructed to avoid direct skin contact with others and sharing clothing or personal items, and restrict activities such as wrestling or swimming.
  • Continue treatment for 1 week after symptoms disappear (except with terbinafine).
  • If symptoms worsen, contact pharmacist or physician.

Assess Benefit

  • Follow-up in 7 days to assess initial effect.
  • Refer to physician if:
    • Symptoms not improving
    • New lesions or affected area spreading
    • Pain, swelling or more redness as occured
    • Severe sensitivity to medication
  • If symptoms are improving, advise patient to continue treatment and for 1 week after symptoms disappear (except with terbinafine).

Assess Adverse Effects

  • Minor redness, itching or stinging does not usually require discontinuation.
  • If symptoms persist or are severe, may indicate contact dermatitis reaction to components of cream. Advise patient to stop therapy and refer to physician.
Products

Detailed information on contraindications, cautions, adverse effects and interactions is available in individual drug monographs in the CPS (e-CPS), Lexi-Comp, AHFS, www.drugs.com or other reliable drug monograph references. For comprehensive drug comparisons, see RxFiles charts (www.rxfiles.ca).
This information should be routinely consulted before prescribing.

OTC Products

 

Ingredient

Brands

Dosage / Directions

Tolnaftate 1%

Tinactin
Generics


Apply twice daily for four weeks.

Recommend using for one week after resolution of symptoms to prevent recurrence

Clotrimazole 1%

Canesten
Generics

Miconazole 2%

Micantin
Monistat
Generics

 

Prescription Products

Ingredient

Brands

DIN

Dosage / Directions

Terbinafine 1% cream

Lamisil cream

02031094

Adults and children >12: 
   Apply once daily for 7 days. 
   Improvements persist for up to
   4 weeks

Terbinafine 1% spray

Lamisil spray

02238703

Ketoconazole 2% cream

Ketoderm

02245662

   Apply once or twice daily for 4 weeks.
   

Prescribing and Billing Details
  • pseudoDIN: 00951101
    • Max of 4 claims per 365 days per patient
    • All "tineas" use the same pseudoDIN and thus have a max of 4 claims per 365 days per patient altogether.

  • May prescribe sufficient quantity to treat ONE episode of tinea pedis.
    • Terbinafine: once daily for 7 days only (long duration of action of up to 4 weeks, longer treatment not needed) 
    • Ketoconazole: once or twice daily for 3-4 weeks.  Continue for an additional week after full resolution.
    • For help prescribing the proper quantity of topicals using finger-tip units, see: http://dermnetnz.org/treatments/fingertip-units.html

  • Only products with an official indication from Health Canada for tinea pedis are considered for these guidelines.  Only the active ingredients in the "products" section are approved for pharmacist prescribing.
Treatment Flowchart
Pharmacist Assessment Documents
References / Suggested Reading
  1. Drugs in Pregnancy and Lactation, 6th edition: Gerald G Briggs BPharm, Roger K Freeman MD, Sumner J Yaffe MD By Lippincott Williams & Wilkins Publishers (November 2001) Dynamed Database, Cochrane Database Syst Rev 2014 Aug 4;(8):CD009992
  2. Haaf M. Use of anti-infective agents during lactation, Part 3: Antivirals, antifungals, and urinary antiseptics. Journal of human lactation 2001;17:160-6
  3. Miller P. Dermatological Conditions: Fungal Skin Infections. CTMA. In: RxTx [Internet]. Canadian Pharmacists Association. Available from: http://www.e-therapeutics.ca. (In Saskatchewan available through www.shirp.ca.)
  4. Mallen A. Athlete’s foot. CTMA. In: RxTx [Internet]. Canadian Pharmacists Association. Available from: http://www.e-therapeutics.ca. (In Saskatchewan available through www.shirp.ca.)
  5. Stone S. Antifungal treatment chart. In: RxFiles. Available at www.rxfiles.ca by subscription. (In Saskatchewan available through www.shirp.ca.)
  6. Tinea corporis. In: DynaMed. Available at https://dynamed.ebscohost.com/ by subscription. (In Saskatchewan available through www.shirp.ca.
  7. Goldstein A, Goldstein B. Dermatophyte (tinea) infections. In: UpToDate. Available at www.uptodate.com by subscription.
  8. Fungal skin or nail infections.In: C-Health. chealth.canoe.ca. (Free access)
  9. Ringworm In: Mayo Clinic. www.mayoclinic.org. (Free access)
  10. Ringworm or tinea. In Bluebook – Guidelines for the control of infectious diseases http://ideas.health.vic.gov.au/bluebook/ringworm.asp (Free access)

Prepared by medSask, Your Medication Information Service
Reviewed by Dr. P. Fourie, Family Physician and Dr. Yvonne Shevchuk, Professor, College of Pharmacy & Nutrition.
 Sponsored by the Saskatchewan College of Pharmacists.
Posted May 2010. Updated Mar 2016.