Why does my underarm itch?

What changed before the itching started?

Think about recent changes in deodorant, body wash or laundry detergent. Contact dermatitis is eczema triggered by something touching your skin. An irritant directly damages the skin's outer layer; an allergen triggers an immune reaction. Symptoms can begin hours or days after contact, so the connection is not always obvious.2

Contact dermatitis can cause dryness, cracking, blisters, burning or stinging. A rash can look red on lighter skin and dark brown, purple or grey on darker skin. Fragrance allergy can affect the underarms, and itching can begin before a visible rash. No rash does not automatically rule out a product reaction.23

If itching follows shaving, razor burn or ingrown hairs are possible causes. Tender bumps or pustules centred on hairs can occur with folliculitis, inflammation around hair follicles that shaving or waxing can provoke.14

Is the skin fold damp, sore or peeling?

Heat, trapped moisture and skin rubbing together can cause intertrigo, inflammation in a skin fold. The area can become moist, cracked or peeling. Intertrigo is not automatically a yeast infection: inflammation and infection can occur separately or together.45

Candida yeast thrives in warm, moist areas. An underarm yeast infection commonly causes an intensely itchy red rash, sometimes with burning, scaling, swelling or small surrounding spots. Yeast infections are more common during pregnancy, while taking antibiotics, and in people with diabetes or weakened immune systems. Appearance alone is not a reliable reason to choose a treatment yourself.6

What can you do now?

1. 1Stop using a product that seems to trigger the itching. Avoid perfumed deodorants, soaps and moisturizers while the area is irritated.
2. 2Wash daily and after sweating, using cool or lukewarm water. If soap aggravates dryness, use an emollient soap substitute. Avoid long showers and excessive washing.
3. 3Dry the underarm folds completely. A hair dryer on its cool setting can help.
4. 4Pause shaving until the itching has settled. Choose loose clothing and avoid wool or other fabrics that irritate the area.
5. 5For dry skin, apply an unperfumed moisturizer regularly. Ease itching with a cool damp towel, and pat or tap rather than scratch.

A cool hair dryer can help dry underarm folds, giving a hair tool a job outside its usual department.4

For mild intertrigo without infection, a petroleum or zinc oxide barrier can reduce friction. Keeping the area clean and dry also helps prevent yeast infections returning, without requiring a product called an underarm detox.56

Which cream helps, and how long does it take?

Treatment depends on the cause. A pharmacist can help with moisturizers for dry, irritated skin. Yeast infections need antifungal treatment; bacterial infections can need antibiotics. Strong steroid creams are best avoided in underarm folds because they can thin the skin. If the cause is unclear, a clinician can examine the area and sometimes test a skin scraping or swab.245

Contact dermatitis usually improves when the trigger is identified and avoided. A yeast rash should start clearing within two weeks of antifungal treatment. Seek medical advice if itching persists, worsens or keeps returning rather than repeatedly changing creams.267

When should you see a doctor?

Contact a doctor for a lump or swollen glands, severe pain, fever, a new skin growth, a spreading rash, or itching that prevents sleep. If you are pregnant, discuss itching with your doctor or midwife. If itching starts after a medicine change, ask the prescriber about it; medication adjustments should be directed by them.17