Purpuric Rashes

Purpura means purple. A purpuric rash usually results from bleeding into the skin from small blood vessels. Although a purpuric rash is most obvious on the skin, it can occur on any body surface, including the lining (mucous membrane) of the mouth and on body organs.

What are the symptoms?

There are many wonderful things associated with the colour purple. Think purple flowers, purple grapes and Purple Rain, Purple Rain. Unfortunately, when it comes to skin rashes, purple is not so great. It usually means small spots of blood have leaked into the skin. It's easy to tell if you have a purpuric rash rather than another spotty rash because if you press on the skin with an empty drinking glass the spots won't fade. 

Depending on the cause, you may notice other odd things happening like joint pains, fevers or tummy pains. Because so many conditions can cause a purpuric rash, I could devote the rest of this leaflet to all the possible symptoms that you may notice. This would be immensely boring for all of us, so I won't even try.

Read more about the symptoms of purpuric rashes.

What are the causes?

Now we are getting to the meaty part. Causes of purpura have conveniently divided themselves into two groups depending on the platelet count (platelets are tiny blood cells that help your blood to clot). Purpura can be caused by conditions in which the platelet count is normal (non-thrombocytopenic) and those in which it is low (thrombocytopenic). 

Non-thrombocytopenic causes can be further divided into:

  • Those you were born with such as various inherited causes (for example, Osler-Weber-Rendu syndrome - try memorising that to impress your friends) and viruses caught from your mum while you were in the womb.
  • Those you acquired after you were born (for example, severe infections, allergies, reactions to medicines).

Thrombocytopenic causes can be divided into:

  • Those caused by bone marrow failure (for example, leukaemia).
  • Those causing increased breakdown of platelets (for example, immune thrombocytopenia, viruses again).
  • Those affecting the blood clotting system (for example, disseminated intravascular coagulation).
  • Other rare causes (for example, rapid blood transfusion).

Learn more about the causes of purpuric rashes.

How is it diagnosed?

Expect the doctor to ask you lots of questions. They are not being nosy but may genuinely need to know an awful lot about your health, the sort of medicines you sneak into your local pharmacy to buy and your lifestyle. They may also ask you about any recent travel abroad. Unfortunately, what happens in Benidorm, doesn't always stay in Benidorm.

The doctor will have a look at your rash and probably do a quick all-round examination. At this point they will hopefully look less puzzled than they did at the beginning of the consultation. They will then slowly and with great dignity place their hands on the computer keyboard, the better to produce reams of blood test request forms. The good news is that usually a hundredweight of these forms still only equates to one needle in the arm. You will most likely have a full blood count, a liver function test and tests of your immune system. You may need some other fancy tests, depending on what your doctor is looking for.

Find out more about the diagnosis of purpuric rashes.

How is it treated?

How long is a piece of string? The treatment will depend on the cause and we would find a list of possible treatments even more boring than a list of possible symptoms.

The outlook (prognosis) depends on the cause and there isn't always an easy answer to some of the underlying conditions. If there isn't an effective cure, you may have to resign yourself to living with the rash.

There's just one treatment that all patients with purpuric rash have if their platelet count is very low and that's a platelet transfusion. If that happens you'll be a pretty rare and special person. You might as well buy a lottery ticket. It's called karma.

Read more about the treatment of purpuric rashes.

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  • Purpura; University of Maryland Medical Centre
  • Maher GM; Immune thrombocytopenia. S D Med. 2014 Oct 67(10):415-7.
  • Purpura; Internal Medicine Reference
Author:
Dr Laurence Knott
Peer Reviewer:
Prof Cathy Jackson
Document ID:
29413 (v1)
Last Checked:
08 July 2017
Next Review:
07 July 2020

Disclaimer: This article is for information only and should not be used for the diagnosis or treatment of medical conditions. Patient Platform Limited has used all reasonable care in compiling the information but make no warranty as to its accuracy. Consult a doctor or other health care professional for diagnosis and treatment of medical conditions. For details see our conditions.