The exact cause of rosacea is unknown. One theory is that it may result from oversensitive blood vessels in the face. Because rosacea causes increased warmth in the skin, bacteria may grow, causing the pimples and bumps.

Tiny mites (Demodex folliculorum) that normally live on our skin may also play a role: People who have rosacea have more of these mites on their faces than those who don't have the disease.

Flare-ups often start when certain triggers cause the blood vessels in the face to dilate, which causes redness. Common triggers are sun, exercise, hot weather, emotional stress, spicy foods, alcohol, and hot baths. Swings in temperature from hot to cold or cold to hot can also trigger a flare-up of rosacea.

Many people with this skin condition have a family history of rosacea.¹

There may be a link between rosacea and Helicobacter pylori bacteria, which causes an infection in the stomach, although studies are unclear.

Alcohol and poor hygiene do not cause rosacea, as was believed in the past. But drinking alcohol may trigger facial flushing and can cause symptoms to get worse.