DermNet provides Google Translate, a free machine translation service. Note that this may not provide an exact translation in all languages



Author: Dr Mark Duffill, Hamilton, New Zealand, 2008.

Table of contents

What is pseudoporphyria?

Pseudoporphyria is a condition which closely resembles true cutaneous porphyria (porphyria cutanea tarda, variegate porphyria) but porphyrin tests are normal.

What are the symptoms of pseudoporphyria?

Skin signs include skin fragility and photosensitivity. Tense blisters form at the sites of minor trauma on sun exposed skin, bursting early to leave scabs and erosions. The blisters are most often seen on the hands and feet. They sometimes heal with some scar formation and tiny white cysts under the skin (milia).

A sunburn type rash may also occur.


What is the cause of pseudoporphyria?

Pseudoporphyria is generally due to drugs or other agents which interact with sunlight to cause a phototoxic reaction in the skin. These include:

It may be provoked by:


If there is clinical doubt, biochemical tests will be done to exclude true cutaneous porphyria. This may include blood, urine and faeces samples.

A skin biopsy may be taken from a blister.

Phototesting can be done to confirm to confirm a phototoxic action of the suspected agent.


It is important to withdraw the suspected agent where possible and avoid unnecessary exposure to strong light.

Sun protection measures may include UVB and UVA blocking sunscreens.

Symptoms usually resolve within several weeks but sometimes they are persistent.



  1. Pseudoporphyria , Green JJ Manders SM,  J Am Acad Dermatol 2001 Jan; 44: 100–8. Medline
  2. Nonsteroidal antiinflammatory drug-induced pseudoporphyria: a case series. LaDuca JR , Bouman PH, Gaspari AA. J Cutan Med Surg 2002; 6: 320–6. Epub 2002 Jul 16. Medline

On DermNet

Other websites

Books about skin diseases


Related information

Sign up to the newsletter