What is Pityriasis?

Tricia Christensen
Tricia Christensen

Pityriasis is a flat skin rash, occurring under the skin, which is common in older children and young adults. The rash begins as a single oval shaped mark, sometimes called the herald, which is often missed or is misdiagnosed as ringworm. Additional marks begin to form under the skin, usually affecting the trunk and lower body, though marks can appear on any part of the body.

Sun exposure may worsen a pityriasis rash.
Sun exposure may worsen a pityriasis rash.

Though pityriasis causes an unsightly rash, it is not thought to be dangerous. Presence of a rash that lasts for more than a few days should mean a visit to a physician when possible, to rule out other more serious causes of rashes. The rash is generally not uncomfortable or itchy, as the skin is not raised or irritated. However, the rash can be annoying because it can last for up to three months.

Antihistamines can help reduce itching caused by pityriasis.
Antihistamines can help reduce itching caused by pityriasis.

There are two forms of pityriasis: rosea, described above, and pityriasis lichenoides. Lichenoides can cause scaling, even though its formation resembles rosea. It also suggests one may have an autoimmune disorder. Those diagnosed with lichenoides will probably need follow-up care and testing to rule out HIV, mononucleosis, and certain forms of Hepatitis as these can be causal factors.

Pityriasis lechenoides may be an early sign of HIV infection, which is typically treated with a cocktail of antiretroviral drugs.
Pityriasis lechenoides may be an early sign of HIV infection, which is typically treated with a cocktail of antiretroviral drugs.

Both forms of pityriasis can occur without any underlying symptoms and are thought to be of viral origin. Neither form is particularly contagious, though occasionally in families one will see more than one person with this condition. This is probably a result of exposure to the same viral cause.

Though itching is uncommon with pityriasis rosea, it may be present in the lichenoides form. Treatments proposed are similar to treatments for rashes such as those received from contact with poison oak or ivy. Oatmeal baths and calamine lotion may be helpful. Antihistamines may also reduce itching and promote better sleep at night.

The rash usually resolves by itself and requires no treatment. However, where autoimmune conditions or other viruses have been detected as precursors to pityriasis lichenoides, various treatments may be employed to address these conditions.

Some suggest sun exposure may help reduce the length of time one suffers from this condition. Sun exposure may also cause the rash to worsen, as the skin may be hypersensitive. Additional damage to the skin may occur through sunburn.

The milder form, pityriasis rosea, is in most cases simply an annoying and unattractive rash which must be given time to improve. Should the condition not improve within the time frame given to one by a physician, it is advisable to contact the physician again for further instructions or advice.

The presence of pityriasis lichenoides often prompts doctors to test for HIV.
The presence of pityriasis lichenoides often prompts doctors to test for HIV.
Tricia Christensen
Tricia Christensen

Tricia has a Literature degree from Sonoma State University and has been a frequent wiseGEEK contributor for many years. She is especially passionate about reading and writing, although her other interests include medicine, art, film, history, politics, ethics, and religion. Tricia lives in Northern California and is currently working on her first novel.

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Discussion Comments


I'm 15 and I have this. I went to the doctor to check it out today and I got some medication to clear it up.


Two months ago I visited the US on vacation. There I got this rash called pityriasis rosea. but recently a colleague of mine told me it can lead to auto-immune diseases. is that possible? What are the chances of that happening?


I had two episodes of pityriasis rosea in the past few years. And I have just recently been diagnosed with MS, so there could indeed be a link or relationship.


I have pityriasis which first appeared in my thirties. When I went to the doctor it was the first case she had seen and was fascinated by the herald mark.

I am 48 now and it recurs when I get stressed (although not always). If you are worried about ms then have a test. I am worried now so will take a trip to the doctor.


This is not syphilis as you would not skip a stage so i would advise that you calm down and trust your doctor. As for the hair loss this is most likely a mild form of alopecia that is treatable. don't worry on either account.


I hope you can help me because I am totally freaking out! I read that if you have pityriasis rosea (PR) you should get tested for MS because it is related?! Also how do I know it's not syphilis? I had no signs of the first stage but last year I did loose weight without trying and did experience even hair loss on my head.

My dermatologist said I have a mild case of PR-nothing to worry about, but she did no tests. What do you think?


hiya! i have pityriasis rosea, and i am going on holiday in just 3 weeks! i need to get rid of this quickly because i look so dreadful in my bikini with all this spots everywhere, is there anything which can help me get rid of this !?

please help ! going out of my mind!

francesca xx

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