context: Henoch- Schonlein purpura ( HSP) is a disease involving inflammation of small blood vessels. It most commonly occurs in children. The inflammation causes blood vessels in the skin, intestines, kidneys, and joints to start leaking. The main symptom is a rash with numerous small bruises, which have a raised appearance, over the legs or buttocks. Although HSP can affect people at any age, most cases occur in children between the ages of 2 and 11. It is more common in boys than girls. Adults with HSP are more likely to have more severe disease compared to children. HSP usually ends after four to six weeks -- sometimes with recurrence of symptoms over this period, but with no long-term consequences (recurrences are fairly common). If organs such as the kidneys and intestines are affected, treatment is often needed and it is important to have regular follow-up to prevent serious complications. var s_context; s_context= s_context || {}; s_context['wb.modimp'] = 'vidfloat'; if(webmd.useragent && webmd.useragent.ua.type === 'desktop'){ webmd.ads2.disable Initial Load(); webmd.ads2.disable Ads Init = true; $(function() { webmd.p.pim.increment(); $('.responsive-video-container').insert After('.module-social-share-container'); require(['video2/1/responsive-player/video-loader'], function(video Loader) { video Loader.init({ autoplay: webmd.useragent.ua.type === 'desktop' && ! !s_sensitive, chron ID: $('article embeded_module[type=video][align=top]:eq(0)').attr('chronic_id'), continuous Play: true, cp Options: { flyout: true }, display Ads: true, mode: 'in-article', sticky: true }) }); }); } else { $(function(){ $('.responsive-video-container').remove(); }); } The exact cause of HSP is not known. The body's immune system is believed to play a role in targeting the blood vessels involved. An abnormal immune response to an infection may be a factor in many cases. Approximately two-thirds of the cases of HSP occur days after symptoms of an upper respiratory tract infection develop. Some cases of HSP have been linked to vaccinations for typhoid, cholera, yellow fever, measles, or hepatitis B; foods, drugs, chemicals, and insect bites. Some experts also say that HSP is associated with the colder weather of fall and winter. The classic symptoms of HSP are rash, joint pain and swelling, abdominal pain, and/or related kidney disease, including blood in urine. Before these symptoms begin, patients may have two to three weeks of fever, headache, and muscular aches and pains. Rarely, other organs, such as the brain, heart, or lungs, may be affected. Here are some key details about the symptoms of HSP: Rash. The rash usually appears in all patients with HSP. The initial appearance may resemble hives, with small red spots or bumps on the lower legs, buttocks, knees, and elbows. But these change to appear more like bruises. The rash usually affects both sides of the body equally and does not turn pale on pressing. Arthritis. Joint inflammation, involving pain and swelling, occurs in approximately three-quarters of cases, particularly affecting the knees and ankles. It usually lasts only a few days and does not cause any long-term, chronic joint problems. Abdominal pain. In more than half of people with HSP, inflammation of the gastrointestinal tract may cause pain or cramping; it may also lead to loss of appetite, vomiting, diarrhea, and occasionally blood in the stool. In some cases, patients may have abdominal pain before the rash appears. In rare cases, an abnormal folding of the bowel (intussusception) may cause a bowel blockage, which may require surgery to fix. Kidney impairment. HSP can cause kidney problems, indicated by such signs as protein or blood in the urine. This is usually only discovered on urine testing, since it does not generally cause any discomfort. In most patients, the kidney impairment is mild and goes away without any long-term damage. It's important to monitor the kidney problems closely and make sure they clear up, since about 5% of patients may develop progressive kidney disease. About 1% may go on to develop total kidney failure. The diagnosis of HSP may be clear when the typical rash, arthritis, and abdominal pain are present. A doctor may order some tests to rule out other diagnoses, confirm the diagnosis, and assess its severity. Occasionally, when the diagnosis is uncertain, particularly if the only symptom is the classic rash, your doctor may perform biopsies of the skin or kidney. Urine and blood tests will likely be done to detect signs of kidney involvement and may need to be repeated during follow-up to monitor any changes in kidney function. Although there is no specific treatment for HSP, you can use over-the-counter pain medicines, such as acetaminophen or nonsteroidal anti-inflammatory drugs ( NSAIDs), such as ibuprofen and naproxen for joint pain. In some cases, corticosteroid medication may be used. The rash and joint pain will usually go away after four to six weeks without causing any permanent damage. Bouts of the rash may recur in approximately one-third of cases, but usually they are milder, do not involve joint and abdominal symptoms, and they clear up on their own.