What Is Henoch-Schönlein Purpura?

Henoch-Schönlein purpura (HEH-nok SHOON-line PURR-pyuh-ruh) is a condition that makes small blood vessels get swollen and irritated. This inflammation is called vasculitis (vas-kyuh-LY-tis). It usually affects blood vessels in the skin, joints, intestines, and kidneys.

The inflamed blood vessels can leak blood cells into the skin, mucous membranes, or internal organs, causing a rash called purpura.

Most children with Henoch-Schönlein purpura (HSP) fully recover within a few weeks with no long-term problems.

What Causes Henoch-Schönlein Purpura?

Doctors don’t know for sure what causes HSP. But it’s thought to be triggered by infections (from bacteria, viruses, or parasites). Other possible causes include medicines and food allergies. Some people might have a genetic risk for the condition. Researchers continue to look for the exact cause of HSP.

HSP happens when the immune system doesn't work as it should. A protein called immunoglobulin A (IgA) that normally works to fight infections gets deposited in the blood vessels. This leads to the vasculitis.

Henoch-Schönlein purpura is the most common vasculitis in children. It can happen at any age, but is most common in kids 2 to 6 years old. Usually, boys are affected about twice as often as girls. It happens more often in the fall and winter months.

What Are the Signs & Symptoms of Henoch-Schönlein Purpura?

The most common sign of Henoch-Schönlein purpura is a purplish rash, which looks like bruising. It happens in all cases of HSP, usually on the lower legs and buttocks. It also can appear on the arms, face, and trunk.

Kids also might have:

• pain and swelling in the joints, usually about 1–2 weeks before the rash starts. The knee and ankle joints are usually affected.
• belly pain, usually after the rash
• nausea, vomiting, and blood in their BMs (poop)

HSP can affect the kidneys in some cases. Small amounts of blood or protein get in the urine (pee), which may look bloody.

Symptoms of Henoch-Schönlein purpura usually last for about a month.

How Is Henoch-Schönlein Purpura Diagnosed?

Because the rash happens in all cases, it helps doctors diagnose HSP. They also may order blood tests to check for kidney problems, a urine test to look for blood or protein, and a stool test to check for blood in the poop. If a child’s belly pain is severe, the doctor might order an ultrasound.

How Is Henoch-Schönlein Purpura Treated?

Most of the time, Henoch-Schönlein purpura improves on its own without treatment. Medical care is more likely to be needed if HSP involves the kidneys.

To help your child feel better, the doctor may recommend medicines such as:

• antibiotics, if an infection is causing the HSP
• pain relievers (such as acetaminophen)
• anti-inflammatory medicines (such as ibuprofen) to relieve joint pain and inflammation
• corticosteroids (such as prednisone) for severe belly pain or kidney disease

At home, try to keep your child as comfortable as possible. Be sure they get plenty of rest and drink lots of fluids.

A child with HSP who stops eating or drinking or gets severe belly pain or kidney problems might need treatment in a hospital.

What Problems Can Happen?

The kidneys can be affected in up to half of kids with Henoch-Schönlein purpura. In most cases, this is mild and clears up without treatment. But a few children will develop kidney failure. They’ll need to see a kidney specialist (nephrologist) for regular checkups and blood tests.

HSP can cause intussusception. This is when one part of the bowel slides into another, blocking and cutting off the blood supply of the affected portion. This is a medical emergency that needs care right away.

What Else Should I Know?

Most children with HSP fully recover within a month and have no long-term problems.

Some kids who have HSP get it again, usually a few months after the first episode. If it does come back, it's usually less severe than the first episode.