Is it normal to sweat at night when you have the flu?

Yes. Cleveland Clinic says bacterial and viral infections, including the flu and COVID-19, can cause night sweats as your body responds to the illness. They should stop as you recover.

What temperature counts as a fever?

Cleveland Clinic says most providers call 100.4°F (38°C) measured by mouth a fever.

Why Do I Sweat at Night When I'm Sick? Colds, Flu and Fevers

By the Good Sleep team · October 29, 2026

Woman sick in bed blowing her nose, wondering why she sweats at night when she's sick

Answer: when you're fighting an infection, sweating is part of how your body handles a fever. Cleveland Clinic lists chills and sweating that comes and goes among fever symptoms, and says infections such as the flu and COVID-19 can cause night sweats. Body temperature also runs higher in the evening, so the sweats tend to show up at night. They usually fade as the illness passes.

Cold and flu season is here, and with it the classic sick-night pattern: shivering under every blanket you own at 10 p.m., then waking at 3 a.m. soaked. It feels alarming, but in a short illness it's usually your body doing its job.

Why being sick makes you sweat at night

Fever comes and goes. As a fever climbs you tend to feel cold and pile on covers. When it drops, your body sheds the extra heat through sweat, which is what people mean by a fever "breaking".
Evenings run warmer. Cleveland Clinic notes that body temperature is typically lower in the morning and higher in the evening, so a fever often peaks around bedtime.
You over-bundle. The chills make you reach for extra layers, and they're still on you when the fever breaks.
Medicines wear off. If a fever reducer was keeping your temperature down, the fever can return overnight.

How to get through a sweaty sick night

Dress for both halves. A light, breathable layer plus a blanket you can push off beats flannel pajamas under a heavy duvet.
Keep fluids by the bed. Cleveland Clinic's first advice for a mild fever is plenty of fluids and rest. You lose water every time you sweat.
Change into dry clothes after a sweat, and put a towel over the pillow so you can pull it away when it's damp.
Try a lukewarm bath for a mild fever. Cleveland Clinic suggests about 98°F, not cold water.
Use fever reducers as directed if you're uncomfortable and your temperature is above 101°F, per Cleveland Clinic. Don't give aspirin to anyone under 17.
Keep the room cool, not cold. A comfortable bedroom with lighter covers helps more than turning the heat up.

Sharing a bed while sick

Use separate blankets so your chills and sweats don't keep your partner up, or move to another room for a few nights. If you share a dual-zone bed, each side can be set on its own, which helps when one person is feverish and the other isn't.

After you're better

Sick-night sweats should stop as the infection clears. If they carry on for weeks afterward, or appear when you're not ill at all, that's a different situation worth a check-up. Good Sleep's article on night sweats causes and solutions covers the bed side once you're well, and this guide to the best bedding for night sweats helps if you're replacing soaked sheets.

When to see a doctor

Call your healthcare provider if a fever lasts longer than three to four days, comes with breathing changes, or reaches 103°F or higher in an adult, as Cleveland Clinic advises. Go to the emergency room for a fever with a stiff neck, severe headache, confusion or trouble breathing. See a doctor too if night sweats keep happening after you've recovered, or come with weight loss or a cough that won't clear.

Sources

← All night-sweat situations