Fever and Night Sweats

Reviewed by: HU Medical Review Board | Last reviewed: November 2023 | Last updated: November 2023

Fever, or a higher body temperature than normal, is one of the more common symptoms of Crohn's disease and ulcerative colitis (UC). Crohn’s and UC are the 2 main forms of inflammatory bowel disease (IBD).1,2

There may be several reasons why Crohn’s and UC sometimes cause fever and night sweats. Night sweats are intense feelings of heat that occur during sleep and often cause people to wake up chilled and sweaty. Up to half of people with IBD will experience a non-digestive issue like this.3

Some reasons why Crohn’s and ulcerative colitis may cause fever and night sweats include:1,4

  • Inflammation throughout the body
  • Infections from complications like abscesses and toxic megacolon
  • Side effects of drugs used to treat IBD

The fever and night sweats of Crohn’s and UC can vary from mild to severe, depending on whether symptoms are flaring or in remission. Fever and night sweats may also be caused by conditions other than Crohn’s or ulcerative colitis.4

What is a fever?

A fever is a body temperature of 100.4°F or higher. Normal body temperature averages 98.6°F, but it can be slightly higher or lower in some people. It also changes throughout the day.5

Your temperature is usually highest in the evening and during a menstrual period. Your body temperature may be higher after you exercise or eat, spend time in high heat or humidity, and feel intense emotions.5

If you have a low-grade fever, drink plenty of water and rest. If you have a high fever (103°F or higher), call your doctor right away. If you have a fever and feel pain, you may be developing a serious infection and need to call your doctor.1,5

IBD drugs and fever

Some medicines used to control the symptoms of Crohn’s and UC may cause a fever. Some examples include:4,6-8

  • Vedolizumab (Entyvio®)
  • Sulfasalazine (Azulfidine®)
  • Mesalamine (Apriso®, Canasa®, Delzicol®, Lialda®, Pentasa, Rowasa®)
  • Balsalazide (Colazal®)

Your doctor may suggest that you treat a mild fever with an over-the-counter drug like acetaminophen (Tylenol®). People with IBD often need to avoid nonsteroidal anti-inflammatory drugs (NSAIDs) such as aspirin, ibuprofen (Motrin®, Advil®), or naproxen (Aleve®). NSAIDs help reduce pain but can irritate the gastrointestinal tract.4

A high fever that does not go away may be a sign that your IBD symptoms are beginning to flare or you are developing a serious infection. Contact your doctor if your fever does not get better with over-the-counter treatment or lasts more than a day or 2.1

IBD, other conditions, and night sweats

Night sweats can be caused by the fever of IBD or many other health conditions, including menopause, stroke, sleep disorders, or thyroid disease. Some medicines also can cause night sweats. And simply sleeping in a room that is too warm or using too many covers can lead to night sweats.3

If night sweats cause you to lose sleep on a regular basis, talk to your doctor. They may want to check your other IBD symptoms or test you for other health conditions.3

Sleep problems and IBD

Pain, fever, and night sweats may make it harder to get a good night’s sleep. In fact, people with IBD often have trouble sleeping.9

Waking up in the night because of night sweats can increase fatigue. When you do have night sweats, try to get cleaned up and comfortable without turning on the lights or getting out of bed. Other tips you can try to help you get more rest with night sweats include:10

  • Wear lightweight pajamas and use light blankets or just sheets.
  • Keep the bedroom cool with the air conditioner or a fan.
  • Sleep on top of 1 or 2 towels. If you sweat in the night, you can change the towel. This will help you avoid having to change soaked sheets in the night.
  • Keep an extra set of pajamas next to your bed so you can change your clothes easily.

You can also improve your chances of getting a good night’s sleep by practicing good sleep habits. Things that can make a difference in how well you sleep include:9

  • Getting some exercise each day
  • Sticking to a schedule of waking up and going to bed at the same times each day
  • Avoiding daytime naps
  • Avoiding caffeine late in the day
  • Starting to relax at least 1 hour before bedtime

If fever, night sweats, or sleep problems happen regularly, try keeping a symptom diary. This record of how often your symptoms occur and how intense they are can help you and your doctor discover what is causing your fever or night sweats.

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