The Bottom Line

Henoch-Schonlein purpura (HSP), now also called IgA vasculitis, is the most common systemic vasculitis (blood vessel inflammation) in children. It causes a distinctive purple-red rash on the legs and buttocks, along with stomach pain and joint aches. About 4–8 per 100,000 children develop HSP every year, most between ages 3 and 10. The good news: most cases resolve on their own within a few months. The most important thing to watch for is kidney involvement, which affects 20–50% of children with HSP and can occasionally be serious.

What Is Henoch-Schonlein Purpura?

Henoch-Schonlein purpura (HSP) — its modern name is IgA vasculitis — is a condition where the immune system causes inflammation in the small blood vessels throughout the body. This inflammation happens because a specific type of antibody called IgA (immunoglobulin A) forms clusters (immune complexes) that deposit in blood vessel walls, triggering damage.

HSP is the most common form of systemic vasculitis in children. It primarily affects children aged 3–10 years and often follows an upper respiratory tract infection (like a strep throat or cold). Boys are affected slightly more often than girls.

What Are the Signs and Symptoms?

HSP has four classic features. Your child may have all four, or just some of them:

1. The Purpura Rash (Most Recognizable)

The hallmark of HSP is a distinctive skin rash. Here is what to look for:

  • Red to purple, raised spots (palpable purpura) — they feel raised when you run your finger over them
  • They do not turn white (blanch) when you press on them — this is a key feature
  • Concentrated on the lower legs, buttocks, and sometimes the arms
  • Often appear in waves or "crops" over days to weeks
  • May fade leaving temporary brownish discoloration, but no permanent scarring

2. Abdominal Pain

Stomach cramping and pain is common. This happens because the blood vessel inflammation extends to the intestinal lining. In most cases it is mild to moderate. Rarely, it can cause serious complications like intestinal bleeding or a blockage called intussusception, which requires urgent care.

3. Joint Pain and Swelling (Arthritis)

The knees and ankles are most commonly affected. Joint pain and swelling can be uncomfortable but typically resolves as the illness improves and does not cause permanent joint damage.

4. Kidney Involvement

This is the most serious potential complication of HSP. About 20–50% of children with HSP develop some degree of kidney involvement, ranging from mild (blood or protein in the urine detectable only by testing) to severe kidney inflammation (glomerulonephritis). Kidney problems may develop or worsen even after the rash and other symptoms have improved, which is why follow-up urine and blood tests are essential.

What Causes HSP?

The exact cause is not fully understood. HSP is not contagious. Common triggers include:

  • Upper respiratory infections, including strep throat (Group A Streptococcus is frequently linked)
  • Other infections (viral or bacterial)
  • Certain medications or vaccines (in rare cases)

Genetic factors likely play a role, as some children are more prone to this immune response than others.

How Is HSP Diagnosed?

HSP is typically diagnosed based on clinical features — especially the characteristic purpura rash on the lower extremities combined with stomach pain, joint symptoms, and/or urinary abnormalities. Key tests include:

  • Urinalysis: Checks for blood or protein in the urine (kidney involvement)
  • Blood pressure monitoring: Elevated blood pressure can signal kidney problems
  • Blood tests: Platelet count is normal in HSP — this is important because it distinguishes HSP from other causes of purpura (like low platelets)
  • Skin biopsy: Can confirm IgA deposits in blood vessel walls if the diagnosis is uncertain

How Is HSP Treated?

Most children with HSP recover fully without specific treatment. Management focuses on:

  • Rest and hydration during the acute phase
  • Pain relief: Ibuprofen or acetaminophen for joint pain and fever (ibuprofen is used with caution if there is kidney involvement)
  • Corticosteroids (prednisone): May be prescribed for severe stomach pain or significant kidney disease to reduce inflammation
  • Monitoring kidneys: Regular urine testing and blood pressure checks for weeks to months after diagnosis — even when your child feels fine
  • Stronger kidney treatment: For children with progressive kidney disease, immunosuppressive medications may be needed

When to See a Dermatologist or Doctor

  • Your child develops a non-blanching purple-red rash on the legs or buttocks — especially combined with stomach pain or joint pain
  • Your child is having significant abdominal pain, vomiting, or blood in the stool
  • Urine appears dark, tea-colored, or pink-red (blood in urine)
  • Your child's blood pressure is elevated
  • Symptoms are severe or your child seems very unwell
  • Follow up regularly after diagnosis — kidney problems can develop or persist after the rash resolves

Frequently Asked Questions

What causes the purpura rash in HSP?

The rash happens when IgA immune complexes deposit in the walls of tiny blood vessels in the skin. This triggers inflammation that causes the vessels to leak red blood cells into the surrounding tissue, creating the purple spots. Because the bleeding is directly into the tissue (not into a capillary you can press closed), the spots don't turn white when pressed.

Will the purple spots leave permanent scars?

No. HSP purpura resolves without scarring. You may notice a temporary brown or copper discoloration as the old blood is absorbed — this fades over weeks.

How long until my child recovers?

Most children recover within 3–6 weeks. However, the rash and symptoms can come in waves, and the disease can occasionally last several months. Kidney involvement may persist longer, which is why follow-up visits are important even after your child feels better.

Can HSP come back?

Yes, recurrence is possible though uncommon. Some children experience one or more relapses, which is another reason ongoing monitoring is valuable. Most recurrences are milder than the initial episode.

References

  1. Paller AS, Mancini AJ. Hurwitz Clinical Pediatric Dermatology. 5th ed. Elsevier; 2016.
  2. Ozen S, Pistorio A, Iusan SM, et al. EULAR/PRINTO/PRES criteria for Henoch-Schonlein purpura. Ann Rheum Dis. 2010;69(5):790-797.
  3. Habif TP. Clinical Dermatology: A Color Guide to Diagnosis and Therapy. 6th ed. Elsevier; 2016.
  4. Narchi H. Risk of long term renal impairment and duration of follow up recommended for Henoch-Schonlein purpura. Arch Dis Child. 2005;90(9):916-920.
  5. Ronkainen J, Nuutinen M, Koskimies O. The adult kidney 24 years after childhood Henoch-Schonlein purpura. Lancet. 2002;360(9334):666-670.
  6. Mollica F, Li Volti S, Garozzo R, et al. Effectiveness of early prednisone treatment in preventing nephropathy in Henoch Schonlein purpura. Eur J Pediatr. 1992;151(2):140-144.

Trusted Resources

Always consult a board-certified dermatologist and your child's pediatrician or nephrologist for diagnosis and monitoring of Henoch-Schonlein purpura, especially regarding kidney health.