Here’s Why Your Hair Is So Greasy—And What You Can Do About It

If you’ve ever dealt with greasy hair, you’ve probably asked yourself more than one time, “Why is my hair so oily?” while shouting at your reflection in the mirror. (OK, maybe that’s a little dramatic. But still, it’s frustrating!) Having oily hair can make you feel like you’re doing something wrong with your hair care routine, like your hair is dirty, or just make you feel generally embarrassed. It’s not fun. And what can be even more difficult is how unpredictable greasy hair can be—while some people have chronically oily hair, for others, the oiliness seems to come on out of nowhere: One day your hair is normal, and the next, you wake up with greasy strands. So why does this happen? Well, there are actually a lot of different reasons your hair may be getting greasy so fast. SELF spoke to hairstylists and a dermatologist to answer commonly-asked questions about the causes of oily hair and to get their solutions for oily hair treatment.

What causes oily hair?

Before we dive into the variety of factors at play, it’s important to understand exactly what is at the root of oily hair. That answer, at least, is simple: our scalps. “Our scalps are loaded with oil glands, just as our faces are. Oil production is controlled by our genes, and that’s not something we can voluntarily control,” Joshua Zeichner, M.D., director of cosmetic and clinical research in dermatology at Mount Sinai Medical Center, tells SELF. Thus, that potentially unpredictable oily hair. Cue the aforementioned frustration!

Though we can’t control our genetics, which are also responsible for hormone production and hair type, there are ways to manage oily build-up on your hair’s ends and roots. For instance, you can change up how often you wash your hair, finding a good regimen that meets your needs. Or you can adjust the type of shampoo you’re using, depending on what your stylist or colorist recommends. (Or just based on some experimentation.) 

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Why is my hair getting oily so fast?

The most common (and maybe most obvious) answer to the question “why does my hair get greasy so fast” is because it’s not being washed frequently enough. Hairstylist at SCK Salon Devin Toth tells SELF this is the number one cause for oily hair. “Especially if you tend to have an oily scalp, it is important to wash your hair more frequently than you would otherwise,” Dr. Zeichner adds. “The oil has only one place to go, and that is out. Washing your hair helps remove the built-up oil from your hair.” 

How often you need to wash your hair is highly dependent on things like your hair type, how much you exercise, and more. For instance, if you have natural hair, a generally non-oily scalp, and tend to do low-impact activities like yoga, you won’t need to wash your hair as often for oil-prevention purposes as someone who has thin, fine hair, more natural oil production on their scalp, and who does intense boxing workouts multiple times per week. 

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Why is my hair so oily even after I wash it?

There are some obvious potential reasons behind this, like using shampoo that doesn’t clean thoroughly enough. But there’s also a more surprising potential reason. Although there’s not scientific research to back this up, a lot of people anecdotally experience greasy hair they chalk up to washing too much. So if you notice that your situation doesn’t improve with frequent washing, paradoxically, that might be the root of your problem. Here’s the theory of how this may happen, per Calvin Louis, hairstylist and founder of ManeFrame in Los Angeles: “Over-washing your hair strips your hair and scalp of natural oils. The body remedies this by producing even more oil to make up for lost oils, which then creates a buildup and makes your hair feel and look oily.” 

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How often should you wash your hair if it is oily?

It’s hard to create a rule that works for all hair types here, but there’s probably a maximum: every single day, for example, is most likely too much. Instead, you’ll want to find a careful balance to figure out what your best hair washing schedule is based on hair type, routine, and lifestyle. “People with thin hair wash it more often, with a gentle shampoo,” Toth explains. “People with curly hair wash it less frequently.” 

Not sure if your excess grease is the result of over-washing? Louis suggests going a day or two without washing and seeing what happens or only washing your hair once or twice a week. If your oily scalp improves, you’ve got your answer. (You can also try experimenting with dry shampoo to stave off the oil without actually washing.) If you’re ever unsure, talk to your hairstylist next time you’re at the salon! They’re the only person that may know your hair better than you.

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Can my period cause oily hair?

If you have to ask, you probably already know: yup. File this under “yet another way your period can affect your entire body.” A spike in hormonal levels that happens around the beginning of your flow can cause your oil glands to go into overdrive. (Fun fact: This is also the same reason that you may develop acne breakouts around this time.) As a result, your scalp may feel greasier than at other times during the month, Dr. Zeichner explains. (If you’re on birth control that suppresses these hormonal shifts, though, like combination birth control pills, you might be able to rule this out as the behind your greasy hair.) 

It’s worth switching up your shampoo during your period if this happens to you. Try Neutrogena T/Sal Therapeutic Shampoo ($9, CVS) or LivSo Moisturizing Shampoo ($19, Amazon).

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Do certain hairstyles make oily hair worse?

The big factor here is how tight the hairstyle is. For example, throwing your hair back in a ponytail might be a quick way to cool off and get your hair off your neck, but experts warn that this low-maintenance style can actually make hair greasier at the roots. “Pulling the hair together in a ponytail may lead to the accumulation of oil and dirt on the scalp underneath the ponytail holder,” says Dr. Zeichner. “Essentially, this oil, dirt, and grease get trapped in the tiny crevices between your strands because the rubber band serves as a roadblock.”