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Causes of oily skin

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In this article

Hormones and oily skin
Is oily skin genetic?
Foods that can cause oily skin
Other factors that may cause oily skin
Managing your oily skin


Despite what we might have been told in decades gone past, oily skin isn’t caused by eating chips, as much as acne isn’t caused by eating chocolate.

The causes of oily skin go far deeper than what our diets look like. If you battle with oily skin, you may well be stressed and anxious about it, and asking your mirror on a daily basis, why is my skin so oily?!

Oily skin is a consequence of producing too much sebum. Sebum is an oily, waxy substance that’s secreted by the sebaceous glands in the skin. We need sebum to prevent our skin from drying out. Sebum also provides the skin with a protective layer. But too much sebum, and our skin appears shiny and oily.

The reasons why someone might produce excess sebum are varied. Understanding the cause of your excess sebum and oily skin can help you to significantly manage your skin and stop the shine.

Here’s your definitive guide to the causes and treatments for oily skin.

Hormones and oily skin

Most of the time, we associate oily skin with acne prone teenagers. This isn’t just hearsay, as there is a hormonal link to having oily skin. Teenage bodies are going through a lot of change, mostly linked to surges in hormones, hence why acne is common in this age group.

But oily skin doesn’t always mean having acne or even low level breakouts and spots. Oily skin is a condition by itself, and quite often, it can be caused by hormonal imbalances.

Does testosterone cause oily skin?

Testosterone is an androgen, or male hormone, that’s present in the bodies of women (to a lesser extent) as well as men.

If androgens, including testosterone, levels increase, particularly in women, it can cause an increase in the levels of sebum production. This then leads to oilier skin, and potentially also acne.

Health conditions such as polycystic ovary syndrome (PCOS) can cause testosterone levels to rise in women. Testosterone also rises in both genders during puberty.

Oily skin in pregnancy

When you’re pregnant, your levels of oestrogen, progesterone and oxytocin are fluctuating. Hormones known as androgens are also surging, which can lead to oily skin. This is because androgens increase the production of sebum, the natural oily, wax like substance produced by the skin.

With a higher level of androgens, comes a higher level of sebum, and therefore, oilier skin. Once you’ve given birth, your oily skin should settle down within a few weeks or months.

Oily skin and the menopause

As a general rule, the skin tends to become drier as the menopause approaches as the sebaceous glands that produce sebum become less active with age. But this doesn’t mean that it’s impossible to have oily skin at this time of life.

In the same way as going through pregnancy, going through the menopause can also lead to oilier skin as the body goes through fairly intense hormonal changes.

Does increased oestrogen cause oily skin and acne?

An increase in the hormone oestrogen isn’t likely to cause a change in the skin to make it become oilier. However, a fall in oestrogen levels can.

In women, oestrogen levels fall during the menopause, which can cause oilier skin.

Before a woman reaches the menopause, her levels of testosterone are masked by higher levels of oestrogen and another female hormone called beta oestradiol. After the menopause, when oestrogen levels are lower, testosterone is more able to have its effect on the skin.

As we mentioned above, testosterone causes an increase in sebum production, and therefore, oilier skin.

The thyroid and oily skin

Part of having a thyroid disease such hyperthyroidism (an overactive thyroid) or hypothyroidism (an underactive thyroid) is associated with imbalances in the thyroid hormones.

However, this hormonal imbalance is unlikely to cause oily skin. Quite the opposite in fact. Thyroid disease is more likely to cause dry skin complaints, with rashes, facial flushing and cracking.

If you have oily skin, it’s therefore unlikely to be caused by thyroid disease. (But if you have other symptoms that you think may be caused by a thyroid problem, such as falling hair and fingernails lifting from their nail beds, it’s important to speak to your GP.)

Does cortisol cause oily skin?

Cortisol is a hormone that is released when we feel stressed. As if feeling stressed isn’t bad enough, when levels of cortisol rise, so does the amount of sebum that’s released by the skin. This causes the skin to feel oiler.

This excess oil can lead to spots and outbreaks, hence the reason why we might notice spotty skin within a few days of being very stressed.

Having anxiety can also lead to the release of cortisol and the same problems with oily skin.

Does DHEA cause oily skin?

Another hormone that’s related to oily skin is DHEA (or dehydroepiandrosterone). DHEA helps the body produce the male hormone testosterone which we know an excess of can lead to oily skin.

DHEA is available as a supplement that’s been tentatively linked to helping post-menopausal vaginal dryness, depression, aging and osteoporosis.

The evidence for these benefits is sketchy, but it is known that DHEA supplementation can lead to oily skin, acne and an over growth of hair (hirsutism) as well as an increased risk of certain hormone related cancers.

Is oily skin genetic?

Sadly, having oily skin can and does run in families. If a close relative such as a parent or sibling has oily skin, then the chances are, you will too.

The good news is, oily skin is now better understood than perhaps in your parent’s era, and we now know how to better care for oily skin, which can help you a lot!

Foods that can cause oily skin

OK, so a diet of chips isn’t going to be great for any aspect of health. But as we mentioned previously, it isn’t just high fat, greasy foods that lead to oily skin.

Eating foods with a high fat content can lead to blocked pores and spots around the mouth. This is because the oil can build up around the mouth after eating and cause physical pore blockages from the outside.

But there are certain foods that cause the skin to become oily from the inside, namely dairy products…

Dairy and oily skin

Dairy products such as cow’s milk, cheese and yoghurts can cause the sebaceous glands to go into overdrive and begin producing excess oil.

This is thought to be down to the level of bovine (cow) hormones naturally present in milk and dairy products. These hormones can trick the body into thinking they’re human hormones and cause an increase in sebum production.

If you think that dairy products could be causing your skin to feel oilier, try to avoid them or at least reduce your intake. With the increase in veganism, there’s now plenty of dairy alternatives to choose from in supermarkets too.

Can fish oil make my skin oily?

Oily fish and fish oil supplements are rich in polyunsaturated omega 3 fatty acids. These are good fats that help support a healthy brain and heart as well as healthy skin.

It may feel counterintuitive eating oily fish or taking fish oil supplements to help balance your oily skin. But evidence suggests that omega 3 oils can counteract the effects of the stress hormone cortisol that leads to an increase in sebum production.

An increase in omega 3 in your diet can also help to boost the amount of hydration within the skin cells, helping to balance out oily skin.

Can dehydration cause oily skin?

Dehydration causes dry skin, that much is fairly obvious. But dehydration can also lead to oily skin. This is because staying hydrated means that the sebaceous glands are less likely to become blocked and inflamed.

The healthier the sebaceous glands, the better for the skin all round so the advice, as always, is to stay hydrated.

Does alcohol cause oily skin?

Drinking alcohol to excess on a regular basis will lead to dehydration if you’re not also drinking lots of water to counterbalance the effects of drinking alcohol.

Dehydration leads to dry skin, but as we mentioned above, it can also lead to an increase in oil production. Alcohol can also cause your sebaceous glands to produce excess oil, leading to oily skin. It’s thought this is due to the disruptive effect of alcohol on hormones.

Other factors that may cause oily skin

If your oily skin isn’t related to your hormones, genetics or diet, could it be linked to other aspects of your life or lifestyle?

Does sweating cause oily skin?

If you’re sweating a lot, either because it’s hot or you’re going to the gym, and you don’t have time to wash your face, then you could be adding to your oily skin problems.

Leaving a layer of sweat on your face can cause pore blockages that in turn leads to spots, acne breakouts and a build-up of oil. If you’re unable to wash your face, carry a facial spritz with you to help remove sweat and dirt throughout the day.

Does humidity cause oily skin?

As with sweating, being in a humid environment can cause the sebaceous glands to overproduce sebum. This can build-up and lead to oily skin.

Do hot showers cause oily skin?

Overly long or hot showers can strip the skin of its natural oils, leading to dry skin. But over time, the sebaceous glands could try to compensate for their oil being stripped away, by producing more and more. This will then lead to oily skin.

Try to keep shower time to a minimum and use lukewarm water to be kinder to your skin.

Can shaving cause oily skin?

Having naturally oily skin can cause shaving to feel worse, leading to razor burn and skin bumps. Make sure you always use a clean, sharp razor and plenty of lather to minimise the trauma to your skin.

Managing your oily skin

If you have oily skin, then there are lots of ways you can help to manage your skin and keep oil production under control. Our article on treatments for oily skin goes into detail about topical treatments, medications and therapies that you can use to help.

Having oily skin doesn’t have to mean just putting up with it. It might take some trial and error but you can find the treatment that best supports your skin. We wish you all the best in getting the skin you deserve!



Hannah de Gruchy BSc(Hons)

About Author

Hannah de Gruchy is a freelancer writer who specialises in health and wellness. She has a keen interest in the biology of skin and loves using her words to help separate the real science of skincare from the pseudoscience of some skincare brands. Hannah has a degree in Human Biology and many years’ experience working in laboratories around London. Using this experience, Hannah enjoys turning complex science into interesting, engaging and easy to digest pieces to read. In her spare time, Hannah runs, practices yoga and loves cooking plant based foods.

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