There is no universal number, and anyone who gives you one is usually selling a product or a rule.
How often you should wash your hair depends on your scalp, your hair type, and what you do to it during the day. A man with fine, straight hair and an oily scalp who cycles to work has a genuinely different situation from a man with thick, coarse hair and a dry scalp who sits at a desk. Treating them the same is where most bad advice starts.
What actually makes hair look greasy
The oil is sebum, and it comes from sebaceous glands attached to each hair follicle. The scalp carries a high density of those glands, which is why it turns greasy faster than, say, your forearm. Sebum itself is not the enemy — it coats the hair shaft, keeps it flexible, and helps hold water in. The problem is purely one of quantity and appearance. When there is more of it than the hair can absorb, it sits on the surface, clumps the strands together, and reads as flat and dirty.
How much you produce is mostly down to hormones and genetics, with some influence from heat and sweat. That last part matters in summer: a hot commute or a lunchtime run moves sebum down the hair faster and mixes it with sweat, so the same head of hair can look clean on a cool Tuesday and greasy on a warm Thursday.
Why there is no correct frequency
Frequency is a response to how fast your scalp actually gets oily, not a schedule you impose on it. As a rough guide:
- Oily scalp, fine or short hair: often every day or every other day, because oil travels down a short shaft quickly and has nowhere to hide.
- Normal scalp, medium hair: two or three times a week tends to be plenty.
- Dry scalp, thick, coarse or textured hair: once or twice a week is often enough, and washing more can leave the ends brittle.
Activity shifts all of this. Heavy sweat, gym sessions, and city grime push the frequency up. On days you have genuinely sweated through it, rinsing with water and a light wash is more sensible than leaving salt and grime sitting on the scalp until your next scheduled shampoo.
What over-washing actually costs
Washing too often does not damage your hair in some dramatic way, but it has a real cost. Stripping sebum faster than the scalp replaces it leaves the lengths drier, duller, and more prone to looking frizzy or brittle — especially on longer or coarser hair, where the oil never fully reaches the ends in the first place. If your scalp feels tight or itchy after washing, that is a signal you are cleansing harder or more often than it needs.
The fix is usually a gentler formula rather than heroic scrubbing. A balancing shampoo like the Shampoo is designed to clean without stripping, which means you can wash on the days you need to without paying for it in dryness later.
The myth that washing less "trains" your scalp
You will have read that if you wash less, your scalp eventually "adjusts" and produces less oil. It is a tidy story, but the evidence for it is weak. Sebum output is governed largely by hormones and genetics, not by a feedback loop with your shampoo. What actually happens when you stretch the gaps is that you get used to the look, and the oil distributes more evenly along the hair over a day or two — which is not the same as your glands slowing down.
That distinction is worth holding. If your hair looks greasy by lunchtime, the answer is to wash it when it needs washing, not to tough out a week of it in the hope of retraining a gland that is not listening.
When it is buildup, not oil
Sometimes hair stops behaving for a different reason: residue. Styling product, hard-water minerals, and conditioner can accumulate on the shaft and leave hair limp, coated, and oddly unresponsive to a normal wash. That is when an occasional deep clean with a Detox Shampoo earns its place — used now and then, not daily, to reset the hair before returning to your usual routine.
Persistent flaking, redness, itching, or noticeable thinning is a different matter altogether, and no washing schedule will sort it. If any of those carry on or get worse, see a GP or dermatologist rather than working through more products.