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Anaphylactoid Purpura

What is anaphylactoid purpura?

Anaphylactoid purpura is more commonly called Henoch-Schoenlein purpura or HSP. It is an illness in which small blood vessels get inflamed. It can involve many different organs in the body. The inflamed blood vessels may bleed into the skin and cause a red or purple rash called purpura.

What is the cause?

The cause of this illness is not completely understood. Researchers believe that there is some inflammation (swelling) in the blood vessels, which causes symptoms. The illness is often seen in children who have had a viral upper respiratory infection (a cold) a few weeks earlier. The antibodies produced by the child's body to fight the cold may contribute to development of the illness.

Other possible causes of HSP are medicines, insect bites, cold, chemicals, or certain foods. HSP is not an inherited disease. It is not contagious and cannot be prevented.

What are the symptoms?

HSP can occur with some or all of the following symptoms:

  • Rash: The rash is often located on the buttocks and legs. The rash may first look like hives, but usually it changes to purplish or brownish bruises within 1 to 2 days. There is almost always some rash on the ankles.
  • Painful swelling of the joints: The joints most often affected by pain are the knees and ankles. The joint pain may be severe enough to make your child unable or unwilling to walk.
  • Abdominal pain: If your child has severe abdominal pain or blood in his or her stools, the healthcare provider may need to do tests to rule out other, more serious causes of these symptoms.
  • Fever
  • Blood in the urine.

How is it diagnosed?

HSP is diagnosed with a physical exam. Blood tests may be done to check how well your child's kidneys are working and to check your child' blood count. Your healthcare provider may also check your child's urine for blood or protein, and your child's stool for blood.

What is the treatment?

There is no medicine that can cure this illness. There is also no way known to predict who will get HSP and there is no way to prevent it. The illness may last for several months and the symptoms may come and go during this time. The older your child is, the more likely it is that he or she will experience the symptoms again. Your child will eventually get better on his or her own. Until then, you can treat your child's symptoms.

  • Anti-inflammatory medicines

    The best and safest medicine to give to help with the pain and inflammation of swollen joints is ibuprofen (for example, Advil or Motrin). Use the same dose you use to treat your child's fever. Check with your healthcare provider before you give any medicine that contains aspirin or salicylates to a child or teen. This includes medicines like baby aspirin, some cold medicines, and Pepto Bismol. Children and teens who take aspirin are at risk for a serious illness called Reye's syndrome.

    Acetaminophen (for example, Tylenol) may help with the pain, but it will not relieve swelling and inflammation.

  • Steroid medicines

    Your child's healthcare provider may prescribe a steroid medicine, such as prednisone, to reduce inflammation in the intestine. The steroid may help control pain and intestinal bleeding.

  • Fluids

    Encourage your child to drink plenty of fluids and to eat a normal diet as much as is possible.

How long will it last?

Most children recover from anaphylactoid purpura completely and have no further problems. Rarely, however, the kidneys can be affected. It is important for your child to see a healthcare provider for blood pressure checks and urine tests every 1 to 2 months over the next 2 years.

When should I call my child's healthcare provider?


  • Your child develops a fever and the purplish rash.
  • Your child starts vomiting.
  • Your child's abdominal pain is getting more severe, or there is more blood in your child's bowel movements.
  • Your child has not urinated in over 12 hours.
  • Your child begins to look puffy, especially around the face or eyes.
  • Your child's urine has blood in it.
  • Your child is acting very sick.

Call during office hours if:

  • You have other questions or concerns.
Written by the Section of Pediatric Emergency Medicine, The Children's Hospital, Denver.
Published by RelayHealth.
Last modified: 2010-02-03
Last reviewed: 2009-11-05
This content is reviewed periodically and is subject to change as new health information becomes available. The information is intended to inform and educate and is not a replacement for medical evaluation, advice, diagnosis or treatment by a healthcare professional.
2010 RelayHealth and/or its affiliates. All Rights Reserved.
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