If your hair is sweaty right now, get somewhere cooler, loosen it or tie it up, and gently blot your scalp and hair with a clean towel. Drink water, especially if you have been active or in heat.

Wash your scalp when you can with a mild shampoo, then dry it well. Avoid putting heavy oils or styling products on a damp, sweaty scalp because they can make it feel itchier or greasy.

If this is happening often even when you are cool and resting, or you also have racing heart, shaking, fever, unexplained weight loss, or drenching night sweats, arrange medical advice. Persistent excessive sweating can be treatable. The AAD guidance on hyperhidrosis notes that diagnosis matters because sweating can have different causes.

Sweat by itself does not usually directly cause hair fall.

But if sweat stays on the scalp for long periods, it can worsen itching, dandruff or seborrheic dermatitis, and occasionally fungal scalp problems. Scratching and inflammation can then cause temporary shedding or breakage.

What to do:

See a dermatologist if you have noticeable shedding for over 6-8 weeks, bald patches, scalp redness/scaling/pain, or severe itching. Common hair-loss causes include genetics, stress/illness, nutritional deficiency, thyroid problems, traction from tight hairstyles, and scalp inflammation, rather than sweating alone.

For a sweaty scalp and daily washing, choose a mild, fragrance-free, sulfate-free shampoo. Good commonly available options are:

Use a small amount, massage only with fingertips for about a minute, and rinse thoroughly. Daily washing is fine if you sweat heavily, provided the shampoo is gentle and your scalp is not becoming dry or itchy.

Avoid heavily fragranced shampoos and harsh sulfates such as sodium lauryl sulfate, which can irritate some scalps. The AAD advises gentle, fragrance-free, sulfate-free shampoo for sensitive scalp care.

If you also have flakes or itching, use ketoconazole 1-2% shampoo only 2 times weekly, alternating with the gentle shampoo, rather than using it every day.