Acne triggers
Dairy, your cycle, sugar, sleep, stress, the gym, your pillowcase. Every one of these is a suspect for somebody, and almost none of them is a suspect for everybody. Here’s what the evidence says about each, and how to test it on your own skin with SkinTheory.
Dairy
BSome evidence
Does dairy cause acne?
Possibly. Large studies link milk, especially skim milk, to slightly higher odds of acne, but that's an association, not proof. Test your own skin.
Your period
AStrong evidence
Does your period cause acne? Hormonal breakouts and your cycle
For many people, yes. Surveys suggest roughly half of women notice acne flare before their period, but not everyone does. Tracking your cycle shows whether yours does.
Sugar & fast food
BSome evidence
Does sugar cause acne? High-glycemic food, fast food and your skin
Possibly. Two small trials found a low-glycemic diet reduced acne, and sugary drinks are linked to breakouts, but it isn't proven and some studies found no link.
Alcohol
DLittle direct evidence
Does alcohol cause acne?
Nobody knows. There's very little research on alcohol and acne, and nights out bring late nights, food and stress too. Here's how to test it yourself.
Sleep
BSome evidence
Does lack of sleep cause acne?
Possibly. Poor sleep is linked to worse acne in several observational studies, and the AAD lists too little sleep as an aggravator. Cause and effect isn't proven.
Stress
BSome evidence
Does stress cause acne?
Stress may make existing acne worse. Small studies link exam stress with more breakouts, but they can't prove cause and effect. Tracking shows your own pattern.
Gym & sweat
DLittle direct evidence
Does the gym cause acne? Sweat, equipment and whey protein
Dermatologists say trapped sweat, friction from gear and dirty kit can trigger breakouts, though this rests on clinical experience more than studies. Whey protein evidence is mixed.
Pillowcases
DLittle direct evidence
Can dirty pillowcases and bedsheets cause acne?
Possibly. Pillowcases collect oil, sweat and product, and one study linked changing them weekly to less acne coming back. Evidence is thin, but it's easy to test.
New products
BSome evidence
Is my new skincare product causing acne? Purging vs breaking out
Some acne treatments can make acne look worse at first, though how often is debated. Other products can clog pores. Photos from before you start help tell them apart.
How we grade the evidence
Every trigger guide starts with a grade from A to D for how strong the research is on a link with acne in general. It says nothing about your skin: a trigger graded D can still matter a lot for you, and one graded A might not matter at all. That’s what tracking is for.
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AStrong evidence
Consistently linked. Findings agree, including controlled trials or clear clinical consensus.
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BSome evidence
Linked in studies, not proven. A fairly consistent link in observational studies or small trials, but cause and effect isn’t proven.
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CMixed evidence
Mixed: some studies for, some against. Some studies find a link and others don’t, or the effect is small or inconsistent.
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DLittle direct evidence
Little evidence of a link, or barely studied. Few studies show a link with acne, or it has hardly been looked at. What there is comes mostly from a plausible mechanism or expert advice.
Each guide links its sources so you can read the research yourself. If you spot something we’ve got wrong, tell us.
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