How often should you wash your hair

Wash your hair based on how oily or dirty your scalp gets, not by the bottle or a fixed rule.

Seen from behind, a person works a thick lather through their hair with both hands and a shampoo bar — Photo: Karolina Grabowska (Kaboompics) / Pexels

Area: BodyFrom age 12Time to learn: 10 minutes

Straight hair with an oily scalp may need shampoo every day, while dry, curly, coily, textured or thick hair should be washed when needed and at least every 2 to 3 weeks.

Why it matters

Shampoo is for the scalp, where oil, dead skin and hair products build up. The ends are the oldest and most fragile part of your hair, and working shampoo through the whole length can dry it out. Dermatologists base how often to wash on how oily your scalp gets and on your hair type, so two people in the same house may need very different routines.

How to do it

Work out your type. A day after washing, look at your roots: if they look flat and greasy, you have an oily scalp. If your hair is curly, coily, thick or feels dry, you are at the other end.
Straight hair with an oily scalp: shampoo as often as every day.
Dry, curly, coily, textured or thick hair: shampoo when needed, at least once every 2 to 3 weeks. For Black hair, dermatologists suggest washing once a week or every other week to prevent product buildup, which dries hair out.
Put shampoo on your scalp, not along the whole length of your hair. Massage it in with your fingertips, then rinse well.
Use conditioner after washing. If your hair is fine or straight, put it on the ends only; if it is dry or curly, work it through the whole length.
Wrap your hair in a towel or T-shirt to soak up water instead of rubbing it. Detangle wet hair with a wide-tooth comb, not a brush.
Adjust from what you see. If your scalp looks greasy or you see flakes, you may not be washing often enough. If the lengths feel dry or rough, wash less often and condition the full length.
If you have dandruff, use a dandruff shampoo with zinc pyrithione, salicylic acid, sulfur, selenium sulfide, ketoconazole or coal tar. If your hair is fine, straight or oily, use it about twice a week alongside your usual washing. If your hair is coarse, curly or coily, use it about once a week, if your scalp tolerates it. Some must sit for up to 5 to 10 minutes before rinsing, so read the label. See a board-certified dermatologist if it does not clear.

Common mistakes

Following a fixed rule or the bottle instead of how your own scalp looks and feels.
Scrubbing shampoo through the full length of dry or curly hair, which dries it out.
Rubbing hair dry with a towel, which can damage it.
Skipping conditioner on dry or curly hair.

You can do this when …you can say how often you wash your hair and why, based on your scalp and hair type, and change the routine when your scalp tells you to.