Does Sugar Cause Acne? What the Trials Show About Sugar, Soda and Blood Sugar

There is no proof that sugar causes acne. What the research does show is that diets heavy in sugary drinks and fast-digesting carbs are linked with more acne, and that swapping those carbs for slower ones reduced spots in two small trials, though a third trial found no extra benefit. Sugar looks like a possible aggravator for some people, not a single cause for everyone.

The question is usually framed as sugar, but most of the research is about blood sugar: how fast a food raises it, measured as glycemic index and glycemic load. That difference matters for what you do next, because a bowl of berries and a bottle of soda behave very differently in the body. Here is what the studies tested, how strong each result is, and how to find out whether sugar plays a part in your own skin.

What does the research say about sugar and acne?

The most useful evidence comes from a handful of randomized trials of low-glycemic diets, plus large observational studies of sugary drinks and snacks. A 2022 systematic review in JAAD International looked at 34 higher-quality studies and concluded that high-glycemic diets have a "modest yet significant" link with acne and its severity. It also noted that this is the one diet link backed by randomized trials, which is more than dairy has.

The trials are small, and they don't all agree:

Taken together, the trials point the same direction on hormones and mostly the same direction on spots, with one clear null result. None of them was large, blinded for participants (diets are hard to hide), or long enough to show what happens after a year.

Do sugary drinks make acne worse?

Sugary drinks have the most consistent observational link, which makes sense: they deliver a lot of fast sugar with no fiber to slow it down.

• Chinese university students, 2019. In a study of 8,197 students examined by dermatologists, drinking sweetened tea drinks every day was linked with about 2.5 times the odds of moderate to severe acne. People getting 100 grams or more of sugar a day from soft drinks had about 3 times the odds. Carbonated soda alone just missed statistical significance.
• Shanghai teenagers, 2026. Among 1,299 students aged 11 to 16, sugary drinks, milk tea and coffee drinks were each linked with more acne, and the link grew stronger the more high-sugar, high-fat items students had.
• French adults, 2020. In the NutriNet-Santé study of 24,452 adults, sugary drinks were linked with slightly higher odds of current acne (1.18), and fatty, sugary foods with a stronger link (1.54).

These studies are snapshots. They can't show which came first, and people who drink more soda may differ in sleep, stress or other habits. Still, the pattern lines up across countries and ages, and it fits what the trials found about fast carbs.

How could sugar affect your skin?

The leading explanation runs through insulin and IGF-1. Foods that raise blood sugar quickly push up insulin, and insulin raises IGF-1. A 2009 review in Experimental Dermatology laid out how these hormones can make oil glands grow, increase sebum and boost androgens, all of which feed into acne. IGF-1 also peaks in the teenage years, when acne is most common.

The trials back up parts of this chain. The 2018 study saw IGF-1 fall within two weeks of low-glycemic eating, and the Korean trial found smaller oil glands under the microscope. What hasn't been shown is how much of the effect comes from sugar itself versus the rest of the diet, or versus weight loss, which happened in several of the trials.

Is all sugar the same?

No, and this is where most advice goes wrong. A 2024 UK Biobank study of about 136,000 adults looked at fructose by source. Fructose from whole fruit was linked with higher levels of SHBG, a protein that keeps testosterone in check, and with lower free testosterone. Fructose from sugary drinks was linked with the opposite: lower SHBG and, in women, a slightly higher risk of high androgen levels, which are tied to acne. The effect sizes were small, but the direction split cleanly by source.

That matches the glycemic research. Fiber, water and protein slow down how fast sugar reaches the blood. A rough guide:

• Faster sugar: soda, sweet tea, juice drinks, sweetened coffee drinks, candy, white bread, pastries.
• Slower sugar: whole fruit, oats, beans and lentils, whole grains, sweet treats eaten after a meal with protein.

Chocolate is a separate question. In a 2014 study, 14 men with a history of acne swallowed capsules of pure, unsweetened cocoa and had more spots within a week. That hints the cocoa itself, not only the sugar, might matter for some people, but 14 people over seven days is a very small sample. The guide on chocolate and acne covers the newer, larger chocolate trials.

Should you cut sugar for acne?

The evidence doesn't support cutting all sugar as a general acne strategy. The 2024 American Academy of Dermatology guidelines base their recommendations on treatments such as benzoyl peroxide, retinoids and oral medicines, not on diet, because the diet evidence is still limited. And none of the trials asked people to give up sugar entirely. They swapped fast carbs for slower ones while people kept eating carbs.

Forum threads on acne.org show both sides. Some people report clearer skin after cutting sugar, often together with dairy, which makes it hard to know which change helped. Others never cut sugar and rarely break out. Some mention how hard a strict no-sugar diet is to keep up, and that breakouts came back when they stopped. A smaller, targeted change is easier to stick with and easier to read.

What this means for your skin

If you suspect sugar plays a part, test it in a way that gives you a real answer.

• Start with drinks. Sweet tea, soda, energy drinks and sweetened coffee drinks have the most consistent links and are the easiest single change. Keep whole fruit.
• Swap, don't ban. Trade some white bread, pastries and sugary cereal for oats, whole grains, beans and lentils. That's what the trials did. The guide to foods for acne-prone skin has easy swaps.
• Give it 6 to 8 weeks or more. The trials that found fewer spots ran 10 to 12 weeks. Keep your skincare and acne treatment the same so you know what changed.
• Change one thing at a time. Sugar and dairy and acne are often tested together, which makes the result impossible to read. Milkshakes, ice cream and sweet lattes count as both.
• Bring it back on purpose. After the test, reintroduce your usual drink or snack and watch the next two weeks. A pattern that repeats is worth more than one bad week.

Tracking is what turns a guess into a result. The Root Cause app scans your meals and your skin and looks for the foods that line up with your breakouts over time, so you can see whether sugary drinks are one of your triggers without giving up dessert on someone else's advice. Blood sugar also connects to the gut, which is covered in the guide on gut health and acne.

The bottom line

Sugar hasn't been shown to cause acne. Sugary drinks and high-glycemic diets are linked with more acne in large observational studies, and low-glycemic diets reduced spots in two small trials but not in a third. The biggest sources of fast sugar, especially sweet drinks, are the most sensible thing to test, while whole fruit shows no sign of harm. Keep the foods you love, change one thing at a time, and track how your own skin responds.