Henoch-Schönlein purpura (HSP) is a disease that causes small blood vessels to become inflamed and leak blood. It gets its name from two German doctors, Johann Schönlein and Eduard Henoch, who described it in their patients in the 1800s.

The hallmark symptom of HSP is a raised purple-colored rash on the lower legs and buttocks. The spots of the rash can look like bruises. HSP can also cause joint swelling, gastrointestinal (GI) symptoms, and kidney problems.

HSP is most common in young children. Often, they’ve recently had an upper respiratory infection like a cold. Most of the time the disease gets better on its own without treatment.

The main symptom of HSP is a raised red-purple spotted rash that appears on the legs, feet, and buttocks. The rash can also show up on the face, arms, chest, and trunk. The spots in the rash look like bruises. If you press on the rash, it will stay purple rather than turning white.

HSP also affects the joints, intestines, kidneys, and other systems, causing symptoms like these:

  • pain and swelling in the joints, especially the knees and ankles
  • GI symptoms like nausea, vomiting, stomach pain, and bloody stools
  • blood in the urine (which may be too tiny to see) and other signs of kidney damage
  • swelling of the testicles (in some boys with HSP)
  • seizures (rarely)

Joint pain and GI symptoms can start up to 2 weeks before the rash appears.

Sometimes, this disease can permanently damage the kidneys.

HSP causes inflammation in small blood vessels. As the blood vessels become inflamed, they can leak blood into the skin, which causes the rash. Blood can also leak in the abdomen and kidneys.

HSP appears to be caused by an overactive response of the immune system. Normally, the immune system produces proteins called antibodies that seek out and destroy foreign invaders like bacteria and viruses. In the case of HSP, a particular antibody (IgA) settles into blood vessel walls, causing inflammation.

Up to half of people who get HSP have a cold or other respiratory tract infection a week or so before the rash. These infections might trigger the immune system to overreact and release antibodies that attack the blood vessels. HSP itself isn’t contagious, but the condition that started it can be catching.

HSP triggers may include:

There may also be genes linked to HSP, because it sometimes runs in families.

You don’t usually need to treat Henoch-Schönlein purpura. It will go away on its own within a few weeks. Rest, fluids, and over-the-counter pain relievers such as ibuprofen or acetaminophen can help you or your child feel better.

Ask your doctor before taking nonsteroidal anti-inflammatory drugs (NSAIDs) like naproxen or ibuprofen if you have GI symptoms. NSAIDs can sometimes make these symptoms worse. NSAIDs should also be avoided in cases of kidney inflammation or injury.

For severe symptoms, doctors sometimes prescribe a short course of steroids. These drugs bring down inflammation in the body. Because steroids can cause significant side effects, you should closely follow your doctor’s instructions for taking the medication. Medicines that suppress the immune system, such as cyclophosphamide (Cytoxan) may be used to treat kidney injury.

If complications occur within your intestinal system, you may require surgery to fix it.

Your doctor will examine you or your child for HSP symptoms, including a rash and joint pain.

Tests like these can help diagnose HSP and rule out other diseases with similar symptoms:

  • Blood tests. These can evaluate white and red blood cell counts, inflammation, and kidney function
  • Urine test. The doctor may check for blood or protein in your urine, a sign that your kidneys have been damaged.
  • Biopsy. Your doctor might remove a small piece of your skin and send it to a lab for testing. This test looks for an antibody called IgA, which is deposited in the skin and blood vessels of people with HSP. A kidney biopsy can test for kidney damage.
  • Ultrasound. This test uses sound waves to create pictures from inside your abdomen. It can provide a closer look at the abdominal organs and kidneys.
  • CT scan. This test can be used to evaluate abdominal pain and rule out other causes.

More than 90 percent of HSP cases are in children, especially those between the ages of 2 and 6. The disease tends to be milder in kids than in adults. Adults are more likely to have pus-filled sores in their rash. They also get kidney damage more often with the condition.

In children, HSP usually gets better within a few weeks. Symptoms can last longer in adults.

Most of the time, Henoch-Schönlein purpura gets better on its own within a month. However, the disease can reoccur.

HSP can cause complications. Adults can develop kidney damage that may be severe enough to require dialysis or a kidney transplant. Rarely, a section of the bowel can collapse in on itself and cause a blockage. This is called intussusception, and it can be serious.

In pregnant women, HSP can cause kidney injury leading to complications like high blood pressure and protein in the urine.