People occasionally find that their hair still appears greasy after washing. There are several reasons as to why this could be happening.

Persistently greasy hair may be due to an overproduction of sebum, which can sometimes indicate an underlying health condition.

However, the way people wash and care for their hair, and the type of hair products they use, may be the cause.

This article looks at possible causes, treatment and prevention tips, and when to see a healthcare professional.

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Overly greasy hair may be due to seborrhea, which is a relatively common skin condition. Seborrhea occurs when the sebaceous glands create excess oil, or sebum, making the skin and scalp oily.

Most people with seborrhea do not have any underlying health problems. However, some people may have an underlying condition, such as a hormone imbalance.

The type of hair a person has can also affect how greasy their hair becomes. Straight or fine hair is more likely to appear greasy than curly or thick hair. This is because sebum from the scalp can more easily cover the whole strand of hair if it is straight or thin.

If people are using oily or waxy hair products or not cleansing their hair thoroughly, it can cause a buildup of oil, skin cells, and sweat in the hair. This may make it still appear greasy after washing.

Oil may also come from items a person uses on their hair frequently, such as:

  • hair towels
  • hairbrushes or combs
  • hats and scarves

These items can pick up sebum from the scalp when used regularly. Using them without washing them between hair washes may result in the hair become greasy faster.

Some evidence suggests that environmental factors may affect hair and scalp health. A 2015 study found that air pollution was causing an oily scalp in people living in cities, along with other scalp issues such as itching and dandruff.

Diet may also play a part in excess sebum production. According to a 2016 article, dairy and a high-glycemic diet may affect androgen hormones that influence how much sebum the skin produces.

If scaly patches are also present, a person may have seborrheic dermatitis. Seborrheic dermatitis is a common skin condition and can cause scaly, greasy patches on the scalp and skin. Scaly patches may itch or burn and may flake off.

Learn more about sebum here.

Treatment for greasy hair can depend on the underlying cause. Managing excessive oil or changing hair care habits may help.

People with straight or fine hair that gets greasy quickly may need to wash their hair daily to remove excess oil. Using a clarifying shampoo occasionally may also help to remove excess residue and build up.

Using products containing green tea may help to control greasy hair. A 2016 study looked at the effects of a green tea hair tonic on oily hair in 20 healthy participants.

After 28 days of use, the green tea hair tonic significantly reduced oil on the scalp compared to the placebo and tonic base. The positive effects may be due to properties in green tea that help manage androgen conditions.

Some people may benefit from shampoos that contain anionic surfactants. Surfactants help bind sebum and water, which allows for water and shampoo to remove excess oil when washing the hair. Examples include:

  • laureth sulfate
  • lauryl sulfate
  • sarcosines
  • sulfosuccinates

However, anionics can also dry the hair out, which can increase the risk of breakage. People with dry, easily damaged, or dyed hair may need a milder shampoo.

Black people prone to an oily scalp may benefit from a haircare routine that removes oil build-up and prevents breakage if they have tightly coiled or textured hair.

Johns Hopkins suggest people with this hair type cleanse the hair thoroughly no more than once a week. Applying a hydrating conditioner to the hair after washing, avoiding the roots, may help seal in moisture without making the scalp oily.

For Black people with seborrheic dermatitis, the American Academy of Dermatology Association recommend alternating every other day with dandruff and regular shampoo.

Learn more about Black hair here.

People may find the following tips helpful for preventing greasy hair after washing:

  • if possible, wash the scalp once a day, or less frequently for those with easily damaged hair
  • use a clarifying shampoo and a lightweight conditioner, avoiding the roots
  • avoid heavy oil or wax-based styling products, as these can add to residue and build-up
  • regularly clean hairbrushes, combs, hair towels, pillowcases, and headwear
  • try dietary changes, such as a low glycemic diet, to see if this reduces sebum production

Learn more about treating oily hair here.

If seborrhea is not improving with home treatments, people can see their doctor or dermatologist for further treatment and check if they have any underlying health issues, such as a hormone imbalance.

People may also consider seeing a dietitian if they think diet plays a role in excessive oil production.

A doctor or dermatologist may be able to prescribe hair products or medications.

Greasy hair after washing may be due to a person’s hair care routine, an overproduction of sebum, environmental factors, or underlying health conditions.

People may be able to stop hair from becoming greasy as quickly by using a gentle clarifying shampoo and lightweight, non-greasy hair products. If home treatments are not effective, people can see their doctor or dermatologist for further treatment.