Your face produces more sebum than almost any other part of your body because the sebaceous glands on your forehead, nose, and cheeks are both larger and more densely packed than elsewhere. But if your skin feels constantly greasy, the explanation usually involves a combination of hormones, genetics, diet, and environment, each amplifying the others. Understanding which factors are driving your oil production can help you manage it effectively.
Hormones Are the Primary Driver
Sebaceous glands don’t operate independently. They’re controlled by androgens, a group of hormones that includes testosterone. Your sebaceous glands contain an enzyme called 5-alpha-reductase (particularly the type-1 form), which converts testosterone into a more potent version. This potent form binds to receptors inside the gland and triggers two things: the gland cells multiply, and they ramp up fat production. That fat is sebum.
This is why oil production surges during puberty, when androgen levels spike. It’s also why men in their mid-20s to 40s tend to produce the most sebum of any demographic group, according to research in the British Journal of Dermatology that measured sebum output across nearly 200 people aged 4 to 60. The face and scalp are especially responsive because the glands in those areas carry the highest concentration of the enzyme that supercharges testosterone.
For women, hormonal fluctuations during the menstrual cycle, pregnancy, or conditions like polycystic ovary syndrome (PCOS) can push sebum production higher. PCOS in particular causes elevated androgen levels, and oily skin or seborrhea is one of its recognized features alongside irregular periods and excess hair growth. If your oily skin appeared alongside those other symptoms, it’s worth exploring that connection with a doctor.
Your Genetics Set the Baseline
Some people simply inherit more active sebaceous glands. Research on acne (which is closely linked to excess sebum) estimates that about 80% of the variation between individuals comes down to genetics, with only about 20% explained by environmental factors like diet and pollution. Genome-wide studies have identified specific genes involved, including FADS1, FADS2, and FASN, all of which code for enzymes in fatty acid metabolism. Since sebum is essentially a mixture of fats, variations in these genes directly influence how much your glands produce.
If your parents had oily skin, especially through their 20s and 30s, you likely inherited that same tendency. This genetic baseline is something you can manage but not fundamentally change.
Diet Can Make It Worse
What you eat influences your sebum output through a hormone called insulin-like growth factor 1 (IGF-1). Foods that spike your blood sugar quickly, like white bread, sugary drinks, white rice, and processed snacks, cause your body to release more insulin, which in turn raises IGF-1 levels. IGF-1 stimulates the same sebum-producing pathways that androgens do.
A randomized controlled trial found that switching to a low glycemic diet (foods that raise blood sugar more gradually) decreased IGF-1 concentrations in adults with moderate to severe acne. In practical terms, this means swapping refined carbs for whole grains, legumes, vegetables, and proteins that digest more slowly. You won’t eliminate oily skin through diet alone, but if your current eating pattern is heavy on processed carbs, reducing them may noticeably cut down on shine.
Heat and Humidity Increase Output
If your face feels oilier in summer or after a workout, you’re not imagining it. Research published in the British Journal of Dermatology found that sebum excretion changes by roughly 10% for every 1°C shift in local skin temperature. So on a hot day when your skin temperature rises by just a few degrees, you could be producing 20 to 30% more sebum than on a cool one.
Humidity compounds the effect. In dry conditions, some of the oil on your skin evaporates or is absorbed more quickly, making it less noticeable. In humid environments, the sebum sits on the surface with nowhere to go. This is why people in tropical climates often describe their skin as significantly oilier than when they visit cooler, drier regions.
How Much Sebum Is Normal?
Your face produces roughly 1 to 1.5 milligrams of sebum per 10 square centimeters every three hours. That doesn’t sound like much, but the face has about 600 square centimeters of surface area, much of it concentrated in the T-zone where glands are largest. Over a full day, that adds up to a visible film. Some sebum is necessary: it waterproofs your skin, keeps it flexible, and provides a layer of antimicrobial protection. The issue is when production exceeds what your skin can use, leaving you with persistent shine, clogged pores, or breakouts.
What Actually Reduces Sebum Production
Since you can’t change your genetics or stop your body from making hormones, management focuses on the factors you can control.
Topical Ingredients That Work
Niacinamide (a form of vitamin B3) is one of the most studied ingredients for reducing oiliness. At concentrations of 2 to 5%, it targets the fat-producing machinery inside sebaceous gland cells and has been shown to reduce sebum output by 25 to 35% in clinical studies. Look for it in serums or moisturizers that list it in the first few ingredients. Retinol, a derivative of vitamin A, also suppresses sebum production by slowing the rate at which gland cells mature and release their oily contents. It takes several weeks of consistent use to see results.
Dietary Adjustments
Shifting toward lower glycemic foods reduces the insulin and IGF-1 signals that amplify oil production. This doesn’t require a dramatic overhaul. Replacing white bread with whole grain, choosing steel-cut oats over sugary cereal, and reducing soda intake are changes that lower your overall glycemic load meaningfully.
Cleansing Without Overcorrecting
Washing your face too aggressively or using harsh alcohol-based products can strip away surface oil temporarily, but your sebaceous glands respond by producing even more. A gentle, non-foaming cleanser twice a day removes excess sebum without triggering that rebound effect. If you use a moisturizer, choose a lightweight, oil-free formula. Skipping moisturizer entirely often backfires because dehydrated skin signals for more oil production.
When Oily Skin Signals Something Else
In most cases, a greasy face is just the result of active sebaceous glands doing their job a little too enthusiastically. But a sudden increase in oiliness, especially if paired with other changes, can point to an underlying hormonal issue. In women, PCOS is the most common culprit. If your oily skin is accompanied by irregular periods, thinning hair on the scalp, or new facial hair growth, those are signs of excess androgens that warrant investigation.
Certain medications can also ramp up sebum production. Hormonal therapies, some psychiatric medications, and corticosteroids are known triggers. If your skin became noticeably oilier after starting a new medication, that connection is worth raising with your prescriber.