For some people, too-frequent washing can cause damaged hair and a dry, itchy scalp. For others, infrequent washing can make the hair look greasy and lifeless.
Why shampoo your hair?
Washing the hair may be based on a personal preference.
Washing the hair is a lot like washing skin. Water can remove most visible dirt and debris, but might not eliminate odors or oily deposits. Shampoo helps water remove dirt, debris, and odors, such as smoke or sweat effectively.
Shampoos can also remove oil. The hair gets its oil from sebaceous glands that secrete oil called sebum, which keeps the hair moisturized.
Moisturized hair is less likely to break or look dry and frizzy. But too much moisture can make the hair look greasy, limp, and dirty. After several days without shampooing, oil tends to build up closest to the scalp, making any hair around the face look dirty. Most shampoos are designed to strip excess oil, which helps the hair look cleaner for longer.
How shampoo works
Shampoo cleans the hair with chemicals called surfactants. These are soaps that remove surface debris from the scalp and hair. Many shampoos also contain compounds called sulfates, which produce a rich lather that removes oil from the hair. This can help the hair look cleaner, but it can also damage the hair.
Keeping at least some oil on the hair is important to protect the hair from damage. Some people opt to use sulfate-free or moisturizing shampoos to preserve hair health, although there is little evidence that sulfate-free shampoos are less aggressive than regular products.
Other people choose to reduce the number of times they wash their hair. Some people even advocate giving up shampoo altogether.
How often to shampoo your hair
For most people, shampooing the hair is not necessary for good health. Just rinsing the hair with water a few times a week will remove most visible dirt and debris. The decision about how frequently to wash the hair is a cosmetic one based on personal preference.
Rinsing the hair with water between washes may be recommended for people with very dry hair.
People with very dry hair do not need to wash their hair daily, or even every other day. Instead, washing the hair less often will help preserve the natural oils in the scalp and keep hair well moisturized.
Washing their hair weekly or even every other week might be enough for people with very dry hair.
Rinsing the hair with water in between washes can keep it looking fresh without stripping the hair of its moisture.
Hair is more likely to be dry when it is:
- aging or gray
- treated with chemicals, such as dyes or chemical relaxants
Very oily hair may look greasy a few hours after washing, particularly in the summer or after a workout. People with very oily hair might choose to wash their hair daily or every other day.
Using a sulfate shampoo can lengthen the time between washes. Hair is oilier when it is:
- very fine
People undergoing hormonal changes, such as puberty, may also find that their hair gets oilier than usual.
Most people fall somewhere in between these extremes and can wash their hair 2 to 5 times per week based on their personal preference.
The condition of a person’s scalp will also affect the condition of their hair. People with very dry scalps tend not to produce as much sebum. Washing the hair less often can help the scalp remain healthy, prevent itching and flaking, and keep the hair soft and shiny.
People with very oily scalps may develop acne on the scalp or along the hairline and may need to wash their hair more frequently to keep their hair looking clean.
Hair styling preferences
Much of the decision about how frequently to wash the hair depends on personal styling preferences. Some people dislike their hair looking or feeling even a little oily. Others find that their hair is more manageable several days after washing.
People who wear complicated hairstyles or who have very long hair may also prefer to shampoo less often, as less frequent shampoos mean less time spent styling the hair.
Oily or dry?
Assessing whether the hair is oily or dry can help someone decide how frequently to shampoo. A person can help determine their hair type by asking:
- When does the hair look best? Oily hair tends to look best on the day of a shampoo. Normal hair may look best on the following day, while dry hair may not look its best until several days after a shampoo.
- Does the hair break easily? Dry hair often breaks easily and may have split ends. Oilier hair tends to be more elastic.
- How does the hair look? Just looking at the hair may provide some insight. Dry hair may look brittle or lifeless when over-washed, while oily hair may be flat and greasy only a day after washing.
Is shampooing ever medically necessary?
Tar products and medicated shampoos are recommended for people with scalp psoriasis.
For most people, there is no medical need to shampoo at all, as rinsing with water can remove dirt and dandruff. However, some health conditions can benefit from regular shampooing.
People with parasitic infections of the scalp, particularly lice, may need to use special shampoos to get rid of the bugs.
Scalp psoriasis may improve with the use of special shampoos, particularly tar products or medicated shampoos. People with specific skin and scalp conditions should discuss their ideal hair care regimen with a dermatologist.
By contrast, some medical conditions may get worse with frequent washing. Daily shampooing can irritate eczema, very dry skin, and dandruff.
Alternatives to shampooing
Shampooing is not the only way to help the scalp look or feel clean. Some alternatives include:
- Dry shampoo: Dry shampoo is a powdery, fragranced spray that absorbs oil. It can extend the time between shampoos, particularly for people with fine or oily hair. However, dry shampoo does not remove dirt. If used several days in a row, it can also cause a powdery accumulation that irritates the scalp.
- Detergent-free shampoos: Detergent-free shampoos, sometimes called “no-poos,” are shampoos that are free of sulfates and harsh detergents. They gently condition the hair but do not strip it of its oil. These are a good choice for people with dry or curly hair, or those who like to wash their hair daily but who do not want to cause damage.
- Conditioner-washing: Conditioner-washing, sometimes called co-washing, is when a person uses conditioner or a special cleansing conditioner instead of shampoo. For people with normal to dry hair, conditioner-washing may fully replace normal shampoos, particularly if they do not use heavy styling products.
There is no correct amount of times that a person should wash their hair per week. Expectations about how hair should look and how often a person should wash their hair also vary with culture, age, and from decade to decade.
How often someone washes their hair is a personal decision and not one that is likely to affect overall health.