What Is Sweet Syndrome?

Medically Reviewed by Stephanie S. Gardner, MD on April 26, 2022
4 min read

You’ve been running a fever for the past few days. Now, you have a bumpy rash that’s spreading fast and it hurts. These symptoms can point to a number of health conditions, including one you may never have heard of: Sweet syndrome.

Usually, this rare skin condition (also known as acute febrile neutrophilic dermatosis) isn’t serious and clears up without treatment. But it can be triggered by another health problem, such as an infection or possibly cancer. It’s not contagious, so you can’t catch it from -- or give it to -- someone.

Middle-aged women are most likely to get it. But men and even babies can get it.

The biggest sign is the rash that seems to appear out of nowhere a few days or weeks after a fever.

Small red or purple bumps or lumps typically show up first on your arms, legs, face, or neck. But they can pop up in other places, too. They tend to grow quickly and eventually join together to make large patches.

The rash can be painful. You may get blisters or pimple-like bumps. They can break open and become infected.

In addition to fever and rash, other symptoms include:


Most of the time, it happens on its own and doctors can’t find a reason. Other times, it happens when your immune system reacts to another problem, like:

  • Blood cancer such as leukemia or lymphoma
  • Bowel disease, like ulcerative colitis or Crohn’s disease
  • Chest infection or strep throat
  • Colon or breast cancer
  • Injury where the rash is, like a needle prick or insect bite
  • Pregnancy
  • Rheumatoid arthritis

A reaction from a drug also can bring on Sweet syndrome. Possible drugs include common ones such as nonsteroidal anti-inflammatory drugs (Advil, Motrin). But a medication called granulocyte-colony stimulating factor that’s used to help fight infections in some people with cancer is the most common culprit.

Your doctor might be able to tell that it’s Sweet syndrome just by looking at your rash. But you’ll probably have tests to rule out other conditions or look for what might be causing the problem. These include:

  • Skin biopsy: A small sample of the rash is taken and looked at under the microscope for signs of Sweet syndrome.
  • Blood tests: Your doctor may look for a large number of white blood cells called neutrophils or other signs of a blood disorder.

If your doctor thinks another condition might be causing the problem, they also might recommend imaging tests like X-rays or a computerized tomography (CT) scan. That involves X-rays taken from different angles and then put together for a more complete picture.


Sweet syndrome can go away by itself without treatment if it’s not caused by another health condition. But this could take weeks or months.

Corticosteroid pills can help with redness, itching, swelling, and allergic reactions. Steroid creams or gels also may help -- especially with smaller lumps -- and can ease pain, too. If you have very painful or swollen lumps, your doctor might put steroids directly into them.

If cancer or another health problem is causing your Sweet syndrome, treating it can clear your skin. If it’s caused by a drug, the rash probably will go away when you stop taking it.

Most of the time, the rash heals well without leaving scars unless you had open sores. But your skin may be a different color for months afterward.

Sweet syndrome may come back after treatment -- that’s more likely if cancer caused it. Its return may mean your cancer has come back if it was in remission (you no longer had any cancer cells). See your doctor right away if you notice symptoms again.