Your face gets oily because of sebaceous glands, tiny oil-producing glands attached to every hair follicle on your skin. These glands produce a complex mixture of oils called sebum, which includes triglycerides, wax esters, cholesterol, and a compound called squalene. Sebum exists to moisturize your skin and protect it from water loss, but when your glands produce too much, the result is that familiar shine on your forehead, nose, and chin.
What controls how much sebum your glands pump out is a combination of hormones, genetics, age, diet, and even how you wash your face. Here’s what’s actually happening under the surface.
Hormones Are the Primary Driver
Androgens, the group of hormones that includes testosterone, are the single biggest factor controlling oil production. Your sebaceous glands have receptors that respond directly to testosterone and its more potent form, dihydrotestosterone (DHT). When these hormones dock onto receptors inside oil-producing cells, they switch on the enzymes responsible for making fat. More androgen activity means more sebum on your skin.
This is why oily skin often shows up during puberty, when androgen levels surge in both boys and girls. It’s also why men generally produce more oil than women throughout their lives. Research measuring skin oil levels in 300 people found that sebum production in male skin is consistently higher and stays stable with age, while women’s oil production gradually declines over their lifetime.
For women, hormonal shifts during the menstrual cycle, pregnancy, or polycystic ovary syndrome (PCOS) can push oil production higher. PCOS and other conditions that raise androgen levels (a condition called hyperandrogenism) commonly cause oily skin and acne alongside symptoms like excess body hair and irregular periods. If your oily skin appeared alongside those other symptoms, a hormonal imbalance may be the underlying cause.
Your Age Changes Everything
Oil production follows a predictable arc, but that arc looks different depending on your sex. For women, sebum output is significantly higher in their 20s and drops sharply by their 50s. One study comparing women in their 20s to women in their 50s found sebum levels roughly cut in half across all areas measured. Researchers attribute this to age-related changes in the sebaceous glands, particularly after menopause when estrogen and androgen levels both fall.
Men tell a different story. The same study found no significant difference in sebum output between men in their 20s and men in their 50s. Oil levels stayed essentially flat. So if you’re a man wondering why your face is still oily in middle age, the answer is that your hormonal profile simply doesn’t shift as dramatically.
Genetics Set Your Baseline
Some people are just born with more active sebaceous glands, and there’s strong evidence that genetics play a role. Your genes influence the size and number of your sebaceous glands, how sensitive those glands are to hormones, and how efficiently your skin cells produce and release oil. Specific genes involved in skin cell development, including one called ZNF750, have been linked to abnormal oil production and skin barrier problems when mutated. If your parents had oily skin, you’re more likely to deal with it too.
Genetics also determine how your skin responds to the hormonal signals described above. Two people with identical testosterone levels can have very different oil output depending on how many androgen receptors their sebaceous glands express and how actively those receptors respond.
Diet Can Amplify Oil Production
What you eat affects your skin’s oil output through a hormone called insulin-like growth factor 1 (IGF-1). High-glycemic foods, the kind that spike your blood sugar quickly (white bread, sugary drinks, processed snacks), raise both insulin and IGF-1 levels. IGF-1 is a powerful trigger for oil production: it stimulates sebaceous cells to multiply, activates the enzymes that convert androgens into their more potent forms, and directly switches on the fat-making machinery inside oil glands.
Research in acne patients has demonstrated a direct correlation between IGF-1 levels in the blood and the rate of oil secretion on the face. Dairy, particularly milk, has also been implicated because it naturally contains IGF-1 and other growth factors. This doesn’t mean a single slice of cake makes your face greasy, but a consistently high-glycemic diet can keep IGF-1 elevated enough to noticeably increase oiliness over time.
Stress Hormones Play a Role Too
Your body’s stress response system has a direct line to your oil glands. Sebaceous gland cells respond to corticotropin-releasing hormone (CRH), the same signal your brain sends to kick off the stress response. CRH significantly increases oil production in sebaceous cells and also triggers inflammatory signals. This helps explain why stressful periods often coincide with oilier, more breakout-prone skin. The effect compounds with androgens, meaning stress doesn’t just add oil on its own but may amplify the hormonal signals already driving production.
Over-Washing Can Backfire
If you’ve been scrubbing your face multiple times a day with harsh cleansers hoping to control shine, you may be making the problem worse. Stripping all the oil from your skin’s surface can trigger a rebound effect where your sebaceous glands compensate by producing even more sebum. Cleansers that contain harsh detergents, strong fragrances, or drying alcohols are the most common culprits. They damage the skin barrier, and the glands respond by ramping up output to restore the protective oil layer that was removed.
A gentle cleanser formulated for oily skin avoids this cycle. Research testing a mild daily facial cleanser on acne-prone subjects confirmed that it did not damage the skin barrier or cause sebum overcompensation, while harsher alternatives did. The goal of cleansing is to remove excess surface oil without stripping the skin completely.
Skincare Products That Trap Oil
Some products don’t make your skin produce more oil but make existing oil harder to escape. Highly occlusive ingredients form a seal over the skin’s surface, and while that’s helpful for dry skin types, it can trap sebum, sweat, and bacteria against oily skin. The most common offenders include:
- Petroleum jelly: Not comedogenic on its own, but its strong occlusive barrier can seal in excess sebum and bacteria
- Silicones (listed as dimethicone, methicone, trimethicone, cyclopentasiloxane): Low comedogenic rating but similarly occlusive, potentially trapping oil underneath
- Heavy plant oils like coconut oil, which rate high on comedogenic scales and can contribute to clogged pores on already oily skin
If your skin feels oily despite a consistent routine, check whether your moisturizer, sunscreen, or primer contains these ingredients. Switching to water-based or gel formulations often reduces the greasy feeling without sacrificing hydration.
Medical Conditions Worth Knowing About
Sometimes persistently oily skin signals a hormonal or metabolic condition. Hyperandrogenism, where the body produces excess androgens, is the most direct cause and shows up in conditions like PCOS, congenital adrenal hyperplasia, and certain adrenal or ovarian tumors. Oily skin in these cases typically appears alongside acne, excess facial or body hair, thinning hair on the scalp, and menstrual irregularities.
Seborrheic dermatitis, a condition causing flaky, red, oily patches on the face and scalp, involves both overactive oil glands and an overgrowth of a yeast called Malassezia that feeds on sebum. People with a genetic predisposition produce the right conditions for this yeast to thrive, creating a cycle of inflammation and excess oiliness concentrated around the eyebrows, nose creases, and hairline.
If your oily skin is accompanied by any of these patterns, the oiliness itself is a symptom rather than the root problem, and treating the underlying condition typically brings it under control.