Your skin is a window into your health, including your heart health.

Picture this: You wake up, wipe the sleep from your eyes, and head to the bathroom. You flip on the light, look in the mirror, and one puffy eye stares back at you. A swollen eyelid—we’ve all been there.

Most of the time, swollen eyelids are caused by something simple. Maybe you fell asleep without removing your makeup, ate a super salty meal last night, or got bit by a bug. In these cases, a home remedy like a warm (or cold) compress is usually enough to take down the swelling.

But if a swollen eyelid sticks around, you might need to see a doctor to rule out things like infection or an allergy.

Here, experts share the most common reasons your eyelids swell, which ones go away on their own, and which need a doctor’s attention—plus how to prevent puffy eyelids in the first place.

You have a stye

“Think of a stye like an eyelid pimple,” says Ashley Brissette, MD, an ophthalmologist and founder of Daily Practice.

These small, painful red lumps can develop on your eyelid when the meibomian (oil) glands get clogged, she adds.

Styes are typically caused by a bacterial infection, says Y. Claire Chang, MD, a board-certified dermatologist at Union Square Laser Dermatology in NYC. “The resulting inflammation causes redness and swelling,” says Dr. Chang. Sometimes, this swelling can affect the whole eyelid.

Other symptoms of a stye may include the following, per the American Academy of Ophthalmology (AAO):

• A small pus spot at the center of the bump
• Feeling like something is in your eye
• Having a scratchy feeling in your eye
• Being sensitive to light
• Crustiness along the eyelid margin
• Tearing in that eye

How to fix it

Luckily, styes aren’t super serious and tend to go away on their own within a week or two, says Dr. Chang. Try speeding up your recovery time with the following home remedies, per Dr. Chang and Dr. Brissette:

• Use warm compresses: Apply a clean