What causes pimples, and why you’re breaking out now

Pimples form when a hair follicle, the tiny opening we call a pore, gets blocked with extra oil and dead skin cells. Bacteria grow inside it, and your body answers with inflammation and sometimes pus. That’s the NHS’s summary. So when you ask “why me, and why now?”, the answer is usually skin that makes plenty of oil plus a trigger or two. Here’s each step, then the triggers you can change.

What causes pimples: the 4 steps under your skin

Blackheads, whiteheads, papules or cysts: which type is it?

About that blackhead: it isn’t dirt. DermNet NZ puts the dark color down to melanin, your skin’s own pigment, at the surface of the plug, so scrubbing harder won’t shift it. DermNet also notes that this clogged, non-inflamed kind of acne is more common in smokers than in non-smokers.

Why am I breaking out all of a sudden?

Hormone changes top the NHS’s list: the ones around puberty, periods, pregnancy and menopause. It also names polyendocrine metabolic ovarian syndrome (PMOS), the condition long known as PCOS. If breakouts arrive together with irregular periods, mention it to a doctor. Beyond hormones, check these. Where the spots sit can point to an outside trigger, like a strap or a helmet, but a spot’s location alone can’t tell you what’s going on inside.

Does food cause acne? What the evidence says about dairy and sugar

Food is the most searched trigger and the least settled. The AAD’s own summary: there may be a connection, but probably not for the reason you think. Foods that raise your blood sugar quickly, like white bread and fries, may worsen acne. In the biggest study it cites, 2,258 people in the US went on a low-glycemic diet to lose weight, and 87% said their acne improved too. Two small trials, 43 young men in Australia for 12 weeks and 32 people in Korea for 10 weeks, found significantly less acne on a low-glycemic diet than on their usual one. Other studies found no link at all.

Cow’s milk is the other suspect. In a US study, 47,355 women recalled what they ate in high school, and those who drank 2 or more glasses of skim milk a day were 44% more likely to have acne. Whole, low-fat and skim milk have all been linked, the AAD notes, while no study has found that yogurt or cheese leads to more breakouts. These are links, not proof, and some rely on memories from years back, so the AAD calls for more research. Our read: don’t cut a whole food group on a hunch. Track a food you suspect for a few weeks instead, and keep caring for your skin either way, since a diet change alone won’t keep it clear.

Is it fungal acne? How to tell it from pimples

If your “acne” itches, sits mostly on your upper back and chest, and every bump looks like the next, it might be Malassezia folliculitis, often called fungal acne. A yeast causes it, and DermNet NZ describes it as small, uniform, itchy bumps with no blackheads or whiteheads among them, sometimes on the forehead, hairline, chin, neck or upper arms too. Heat and humidity, heavy sweating, thick creams and sunscreens, and antibiotics all make it more likely. It’s easy to mistake for acne, so if this sounds like you, a doctor can confirm it and prescribe an antifungal.

Safety note: Deep, painful lumps, spots that leave scars or dark marks, or skin that turns hot, swollen and red: see a GP, family doctor or dermatologist.