What Causes Oily Hair: 9 Reasons & Solutions


It’s frustrating when you wash your hair, only for it to feel greasy mere hours later. What gives!? Oily hair is an all-too-common problem – but what can you do about it? And what causes oily hair in the first place?

Today, I will be talking about what causes oily hair: from environmental factors to medical reasons for greasy hair. And I will also present a solution for each. 

Once you’ve read through this list of oily hair causes, you’ll know exactly what you need to do to achieve a grease-free hair day, once and for all.

But to understand what causes oily hair, it’s important to understand what oily hair is.

Why does hair get oily?

If you regularly have greasy looking hair, it’s because you have an overproduction of sebum. Sebum is the natural oil produced by the sebaceous glands in your scalp, and it’s actually a good thing!

Sebum helps to moisturize your hair and protect it from damage, so it’s vital for keeping your hair healthy. But it’s when that natural production gets out of whack that you start to have issues. An overproduction of sebum can leave your hair looking greasy and flat. 

So what causes oily hair? Let’s take a look at the most common reasons for excess oil.  

What causes oily hair: 9 possible culprits 

Here is a list of what causes oily hair most commonly:

1. Hormonal changes

Acne is often associated with puberty, and that’s because your body is going through some major hormonal changes in those transformative years. These hormonal changes cause your sebaceous glands to produce more oil than usual, which is why many teens struggle with pimples.

But you have pores all over your body, not just your face. And your scalp produces extra oil when you undergo hormonal changes as well! 

And it doesn't just affect teenagers. If you are taking hormones, are pregnant, are going through menopause, or have a natural hormone imbalance, you could be more at risk for oily hair. 

If you think hormones are what causes oily hair in your case, an endocrinologist may be able to help. They are a doctor that specializes in hormones, and they will be able to assist you in finding a better hormone balance for your body. 

2. Heat & humidity

Your environment can play a major role in your oil production. If you live in a very hot or humid climate, it can make your scalp sweat - and the same is true if you exercise frequently. Your sweat can mix with the sebum on your scalp and make your hair appear extra greasy. 

Even regular exposure to hot styling tools can make your body produce more sebum to protect against heat damage and dryness. 

Try air drying your hair more often, and if you live in a humid environment or get sweaty after workouts, try using a dry shampoo to soak up excess oils between washes.

Just don’t go TOO long between washes. Dry shampoo can clog your pores if used for days on end, which will hurt you more than it helps! 

3. Over-washing 

Woman holding a Bars Over Bottles shampoo bar for oily hair on her left eye

Just as going too long between washes isn’t a great thing for oil control, washing your hair super frequently can be an issue. If you wash your hair every day, the frequent shampooing can strip your hair of natural oils and dry out your scalp.

While you might think removing the oil from the scalp would be a good thing for oily control, it actually has the opposite effect. That’s because your skin will panic from the lack of moisture and will go into overdrive to produce even MORE oil. 

So, how often should you shampoo your hair? That highly depends on your hair type. If you have very fine hair, you can probably get away with washing every 2-4 days. If you have naturally coarse or curly hair, you won’t even need to wash that frequently! 

How often to use conditioner also depends on your hair type, but just remember – you don’t have to condition your hair every time you shampoo it (and vice versa)!

4. Using the wrong products

More often than not, what causes oily hair is a product that’s too heavy or too drying for your hair type. And it’s important to know what shampoo is best for oily hair to ensure your strands are as happy as possible. 

I always recommend natural, lightweight products like shampoo and conditioner bars that are specially formulated for oily hair. These won’t be too moisturizing, nor will they contain any harsh chemicals that can irritate your scalp.

An oily hair conditioner will be designed to hydrate your hair just enough without making it greasy or heavy.

5. Poor diet

Your diet can have a major impact on your health. In fact, eating a diet high in sugar and fat can actually contribute to oily hair. To eliminate this as one of the potential oily hair causes, try to eat a balanced diet with plenty of fruits, vegetables, and lean proteins. 

6. Stress

When you think about what causes oily hair, stress might not be the most obvious. But stress can affect many areas of your body – including your scalp. Stress can cause your sebaceous glands to produce more oil, which leads to chronically greasy strands. 

If you think stress is contributing to your oily hair, try practicing some relaxation techniques like meditation, breath work, yoga, or even going for regular walks outside. 

7. Medical conditions

Did you know there are actually medical reasons for greasy hair? Certain medical conditions, such as polycystic ovary syndrome (PCOS) and hypothyroidism, can also cause oily hair. 

These aren’t the only medical reasons for greasy hair, so it’s worth speaking with your health care provider to rule out any conditions that could be causing excess oil. 

8. Using too much conditioner

Woman applying Bars Over Bottles lightweight conditioner for oily hair on her long hair

Just as using the wrong conditioner can make your hair greasy, if you use a LOT of conditioner, you may be wondering: “Does conditioner make your hair oily?"  

Try to use only a small amount of product when conditioning your hair, and only apply it from the mid-lengths down. Applying excess product, or placing it too close to your roots, can absolutely leave your hair looking greasy. 

9. Genetics

Sometimes, what causes oily hair is simply genetics. If your parents have oily hair, there is a good chance that you might too! This is especially true if you have fine hair, which is more prone to excess oil.

Just make sure to perfect your hair routine with the right timing and products, and it will put your hair in a healthier place.


How to stop your hair from being oily

Now that you know some of the main oily hair causes, let's talk about how to wash oily hair. Here are a few tips for keeping grease at bay:

  • Use a shampoo that is designed for oily hair. Look for products that are labeled as "purifying" or "volumizing." But DON’T reach for a “clarifying” shampoo. 
  • Don't wash your hair too frequently. Aim to wash your hair every other day, or every three days if possible.
  • Use warm water, not hot water. Hot water can strip away the natural oils, which can make your scalp produce more oil.
  • Don't scrub your scalp too hard. Scrubbing too hard can stimulate the sebaceous glands, which can cause them to produce more oil.
  • Rinse your hair thoroughly. Make sure to rinse all the product out of your hair to avoid leaving any residue.

The best products for oily hair

At the end of the day, what causes oily hair can totally come down to your hair products. So let’s make sure your products are NOT what causes oily hair in your case! 

Bars Over Bottles Purifying Shampoo Bar

For the best oil control, it’s important to look for a solid purifying shampoo or even a detox shampoo that is natural, gentle, and lightweight. These won’t strip your hair of its natural oils, they will simply remove excess oils, impurities, and irritants. 

Bars Over Bottles Detox Shampoo Bar

Of course, it’s just as important to find the best conditioner bar for oily hair, which should also be lightweight. If you choose anything too heavily moisturizing, like the products geared towards damaged hair or curls, it will probably be too heavy for your oil-prone hair. 

If you’re looking for some fool-proof products, my shampoo and conditioner for oily hair is natural, sulfate-free, silicone-free, paraben-free, and even 100% plastic-free! These reliable little beauty bars can help ensure your hair is voluminous, vibrant, and refreshed on the regular. 

my beauty bars