Causes of Pityriasis Rosea

Pityriasis rosea is a common skin condition that affects 0.15% of the general population. The condition often occurs in older children and young adults between ages 10 and 40 years and is rare among elderly and infants.

The condition has been described for more than two centuries and has a characteristic rash that begins with a small patch called the “herald patch”. This is followed by spread of a red, scaly, itchy rash to the chest, back, arms and legs. Women are at a slightly higher risk of this condition. 1-7

Is pityriasis rosea an infection?

The exact cause of this condition is still unknown. There are certain factors that lead to the belief that this may be caused by a viral infection.

The reasons for this belief is that pityriasis rosea tends to occurs in epidemics and affects large groups of persons together in a community especially during spring and autumn seasons. This could mean an infectious agent is responsible for the condition. In addition, recurrence is rare and this means that persons getting the rash may develop long lasting immunity to the infectious agent responsible for the condition.

Another significant sign that there could be an infectious agent behind pityriasis rosea is that more than 50% of the patients have some symptoms of feeling unwell before the appearance of the herald patch. This precedence of rash with general feeling of being unwell (termed prodromal symptoms) is common in cases of other viral infections. The course of the disease is also well defined and similar for most affected persons and follows a pattern much like other viral infections like measles or chicken pox.

In addition, some patients also show an increase in B lymphocytes and a decrease in T lymphocytes along with increase in Erythrocyte sedimentation rate (ESR). Lymphocytes are white blood cells that fight against infections so their rise is also significant. In addition, many infections show a rise in the ESR.

What may be causing pityriasis rosea?

Some studies have suggested that a virus may be causing pityriasis rosea. When seen under an electron microscope viral changes and virus particles have been noticed. However ,blood tests for antibodies against the viruses or special tests like polymerase chain reaction for viruses have not been positive to pinpoint a specific virus causing the condition.

Some studies have implicated Human Herpes Virus 6 and 7 in causation of pityriasis rosea. Other infections that need to be considered as causative agents of this condition include Legionella pneumoniae, Chlamydia pneumoniae and Mycoplasma pneumonia. However, these have not been proved.

Studies have suggested that some drugs may lead to drug-induced pityriasis rosea. These include:

  • barbiturates (sedatives)
  • bismuth
  • captopril (used in high blood pressure)
  • gold (used in rheumatoid arthritis)
  • metronidazole (antibiotic)
  • D-penicillamine (chelating agent used in certain poisonings)
  • isotretinoin (anti-aging skin preparation)

Despite these speculations, and occurrence of the rash in more than one person in a household at a time and more than one person in the community at a time, the disease is not contagious and does not spread from one person to another by touching.

Further Reading

Last Updated: Apr 7, 2023

Dr. Ananya Mandal

Written by

Dr. Ananya Mandal

Dr. Ananya Mandal is a doctor by profession, lecturer by vocation and a medical writer by passion. She specialized in Clinical Pharmacology after her bachelor's (MBBS). For her, health communication is not just writing complicated reviews for professionals but making medical knowledge understandable and available to the general public as well.


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  1. Viviane Basílio Viviane Basílio Brazil says:

    Tive na gravidez, isso pode trazer algum problema de pele pro futuro do meu filho?

  2. Tiny Tonka Tiny Tonka United States says:

    I have had this condition for many years now and I believe it might be genetic. My case of PR behaves contrary to everything described above as being characteristic of a virus.  I get outbreaks frequently (even though I am not immunocompromised as far as I know), and my first episode lasted for upwards of 6 months, and began creeping towards my face near the end (which it supposedly does only in rare cases).  I use a special soap to keep it at bay and I haven't passed it along to anyone else, including anyone I've shared a bed with. My PR did not show up until my mid/late 20s and, with my most recent episode, my mom told me, "Oh! I used to get that all the time when I was younger." My episodes are not very painful either and only itch mildly and intermittently. The worst itch was with the first herald patch. With recurrences, I don't even get a herald patch anymore.

    • Leslie Hatcher Leslie Hatcher United States says:

      That interesting. I have had them on and off since childhood, and they have never been diagnosed properly. I'm a nurse, and figured this one out doing my own research. They seem to follow a strep infection. If my kids get strep throat, I get a herald patch. I think I am a strep carrier. Definitely a connection here, as strep causes other outward inflammation s/s like scarlet fever, and PANDAS. Do you get strep throat often? Does anyone around you get it often? Strep I mean.

      • V N V N United States says:

        This is my first time with these rashes and diagnosed with pityriasis rosea by the dermatologist. Like you have mentioned, mine started with a strep infection (mid Jan) (doc. prescribed antibiotics before the culture came back saying it's a strep type B), then I had hives that itches all over my limbs 8-9 days after I started the antibiotics. I went to the doctor, they thought I might be allergic to the antibiotics and had me stopped. Then I got these rashes started around end of March.

      • Keri King Keri King United States says:

        OMW, this is so what me and my daughter have. She was diagnosed about a month and half ago with strep throat and then I got this weird outbreak. Now, I know it as the "herald patch". It looked insane and then  I had a weird ring on my arm. Then I had what looked like bug bites all on my leg, my arm, my chest. Then I started noticing my daughter started to get bumps on her. All along none of them itched! AT ALL! We were told it was scabies by a NP which I now know is all wrong. We then went for a second opinion and he suggested that we were miss-diagnosed and told us to resume to normal lifestyle. Then I broke out in the "christmas tree" rash all over my back! Only lasted two days. My daughter has complained of pain and every now and then. Mind you she is only five years old. She gets strep throat often with real light symptoms. I think she is a carrier as well! This all makes sense now. We are on the healing stage. However, I have read that our next stage is aches and pains then to follow with possible peeling? Not 100% sure where I read this. I hope I can keep everyone posted.

  3. J P J P United States says:

    My first experience with PR ever. My dermatologist says she even got it, while in England, prior to being a derma-student. My family has very little medical history, if at all, apart from few high blood pressure persons. I've been caring for a lot of Mycoplasma patients this winter season and singled out either this (droplet isolation) or my contact isolation patients, which may have induced my skin reaction...I'm thinking it is more to do with a droplet source though since gloves are better barriers than a flimsy mask. I noticed it around Jan. 5; it is now Feb. 8 and minor, non-itchy patches are still sprouting then enlarging.

  4. Nicole Renae Nicole Renae United States says:

    This is my second time with PR. Got it last winter, then this winter....but a lot worse my second time. No strep throat, no any type of illness. I thought maybe the cold dry air and steam/hot water. Plus neither of my parents get it. Spread to my legs and neck. I'm on my 3rd month....but they are fading. Some itching but nothing bad.

  5. Shoba Nair Shoba Nair United States says:

    My son is 17yrs old .He had a 6 occurrences of PR. DR are saying eczema, dermatitis , and PR. I don't know what it is?? Herald patch on his back. tiny rashes on his upper back both sides, inner thighs, and his both arms. when the outbreak comes very hard to get the apt with doctor. I am very frustrated. I work at the hospital. I Never saw this kind of rashes. he is using steroid cream. shoba

  6. Caitlin Phillips Caitlin Phillips United States says:

    I have these dots that have been spreading over two weeks and it seems to be leading to this and idk what to do so I'm going to urge care tommorow cause it's 10 times worse then 9 weeks ago any help ?!

    • Ron Langton Ron Langton United States says:

      Caitlin, I made a longer post but basically go get head and shoulders clinical strength shampoo and put it on your body where you have this dry, wait around 10 minutes then take a shower, also use it on your head.  Do this 3-4 times over the next 3-4 days and you can even do it twice a day.  Then use it in the shower but you dont have to put it on dry before hand.

      Second, get some sun, either tan outside for a what would equal around an hour a day or go to a tanning bed 1-2 times a day.  

      How long you have to do this just depends.  I had to do it for around 3-4 days before I had a very large and noticeable improvement.  Itching was gone after day 3-4 and it's pretty much all gone now about a week after doing this.

  7. Ron Langton Ron Langton United States says:

    I hope this helps some of you as I recently had this and read about a cure someone had found.  

    2 things to do, first, go and get Head and Shoulders clinical strength shampoo (if you can't find this just google what the main active ingredient in it is and find another soap with it in there).  Rub this all of the effected areas about 10 minutes before a shower to your dry body.  Then take a shower and use this on your head as well.  Do this at least 3-4 times then you can start just using it in the shower.

    Second, go tanning or lay out in the sun.  I only did this for maybe an hour total for a couple days.  The combination of sun and this shampoo took care of my Pityriasis Rosea in just 4-5 days after dealing with it for weeks.  It has also worked for many many other people who have tried this and reported back.

    Hope this helps.

The opinions expressed here are the views of the writer and do not necessarily reflect the views and opinions of News Medical.
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