Fungal sweat rash: what it is and how to treat it

Is sweat rash always fungal?

No. Intertrigo means inflammation where skin surfaces rub together. Heat and trapped moisture increase friction and damage the skin. Bacteria or fungi already on the surface can then overgrow and cause a secondary infection. Candida is the most common cause of infection associated with intertrigo. The rash commonly appears under breasts, in armpits, between belly folds, in the groin or between buttocks. Fingers and toes can also be affected. Fungal infections include several different groups, including Candida infections and tinea infections such as jock itch; they are not all the same condition.13

What does fungal sweat rash look like?

Intertrigo can look red or reddish brown, with small bumps on opposing skin surfaces. It can itch, sting or burn. More damaged skin can become raw, cracked, scaly, crusted or weepy. Pus filled bumps, a foul smell or raised tender bumps suggest an infection, but do not identify the organism. Around the anus, Candida can cause bright redness, soreness and small separate spots beyond the main rash. Jock itch more often has an uneven distribution and a scaly, ring shaped border in the groin. These are clues for an examination, not a reliable way to choose a medicine from a photograph.14

How to care for a sweaty skin fold

Mild intertrigo without an infection can sometimes be managed at home. Moisture control and friction reduction address the conditions that keep the fold irritated; they are not substitutes for treating an established infection.2

1. 1Dry the moist fold with a fan or a hair dryer on its cool setting.
2. 2Separate touching skin surfaces with clean gauze or a dry towel.
3. 3Wear loose clothing and fabrics that move moisture away from the skin.
4. 4For mild, uninfected intertrigo, use a petroleum or zinc oxide barrier cream or ointment to reduce friction.

Loose clothing helps moisture escape, which gives the wardrobe a job beyond looking presentable. Medical devices such as braces, splints and artificial limbs can also trap moisture against the skin. If the rash sits under one of these, consider that trapped moisture when discussing care rather than treating the rash as an isolated patch.24

For a rash between the buttocks or around the anus, cleanse with lukewarm water and avoid excessive rubbing. Irritating cleansers, alkaline soaps and wet wipes can worsen irritation in this area. A soft wet washcloth can be less irritating than toilet paper. Wet wipes are not automatically the gentler option, despite having an entire aisle to suggest otherwise. A rash here can also come from contact dermatitis or another skin condition, so repeated irritation deserves an examination rather than repeated antifungal treatment.4

Which antifungal treats sweat rash?

Clotrimazole and ketoconazole are options for fungal infections in skin folds. Clotrimazole 1% external skin cream treats fungal skin infections. Ketoconazole kills the fungus causing the infection and is available as a cream or shampoo. The form matters: a skin fold rash needs directions for skin treatment, not instructions for vaginal treatment or dandruff. Clotrimazole comes in several forms. Follow the packet for the exact product or the directions from your prescriber.56

For clotrimazole external cream, wash your hands before and after applying it. Gently rub a thin layer into the affected area, keeping it away from the eyes, mouth and lips. Half a centimetre of cream covers an area about the size of your palm. The usual schedule is 2 or 3 applications daily for 2 to 4 weeks, depending on the condition. Ketoconazole cream is usually applied once or twice daily for most infections. Follow the relevant product schedule rather than using the two medicines interchangeably.56

Do not choose a steroid anti itch cream alone for a suspected fungal rash: steroids can worsen the infection and make it harder to treat. A clinician can use a low dose steroid for inflammation in selected cases, alongside treatment directed at the cause. More severe fungal infections sometimes need prescription treatment or oral medicine.27

How long does it take to clear?

Fungal skin rashes usually clear over a few days to a few weeks. Ketoconazole usually works within 2 to 3 weeks for most fungal infections. With clotrimazole, see a doctor if symptoms have not improved after 7 days. Finish the instructed course even if the rash disappears sooner, because fungus can remain after the visible rash has gone. Seek review if good home care does not resolve the problem or the rash extends beyond the fold.2567

Who should be especially careful?

Heavy sweating, diabetes, excess weight, pregnancy, a weakened immune system and prolonged or high dose antibiotics increase the risk of fungal rashes. Mention relevant medicines and health conditions at an assessment. Babies also get intertrigo, including diaper rash. Do not assume that an adult product's directions apply to a baby.17

Clotrimazole can usually be used during pregnancy or breastfeeding, but check with a pharmacist or doctor first. If applied to breasts or nipples, wash it off before feeding. Clotrimazole can cause irritation, burning or stinging; get advice if side effects persist or bother you. Ketoconazole can also irritate skin. Clotrimazole used around the genitals can damage latex condoms and diaphragms, affecting their reliability for at least 5 days after treatment ends.56

When should a doctor check the rash?

Have a first suspected fungal rash assessed. Get urgent care for a painful, blistered or infected rash, rapid spreading, a rash covering the body or fever. Pus, foul smell and tender raised bumps also need prompt assessment. Examination and skin scrapings can help distinguish fungus from other causes. Repeated episodes need a prevention plan. Intertrigo itself is not contagious, but some fungal infections pass through direct contact, so the diagnosis matters.17