Exposure to sunlight can affect people with cutaneous porphyrias (largely marked by fragility of sun-exposed skin), and two types of acute porphyrias — variegate porphyria, or hereditary coproporphyria.
The severity of the reaction, however, differs among patients.
Why is sun exposure a problem?
In some kinds of porphyria, porphyrins accumulate in the skin. In high concentrations, they can cause sensitivity to a specific spectrum of visible light, and to ultraviolet A and B radiation (UVA and UVB). While UVB causes sunburn, exposure to visible light and UVA rays, which penetrate the skin more deeply, are primarily what cause a reaction in patients with porphyria.
What precautions should I take?
If you have sun sensitivity, the best thing you can do is to avoid sun exposure. If you must go out during the day, here are some things you can do to help protect your skin and prevent rashes, blistering, or other skin problems.
Cover your skin
Wear a large hat when you are outside, and clothes that cover exposed skin. For example, wear long-sleeve shirts, long pants, and closed-toe shoes. Wear gloves while driving or otherwise exposing your hands. The fabric of your clothes should be close-knit, so little light can pass through.
If you are walking, carrying an umbrella may also be a good idea.
Use sunscreen on any areas that are difficult to cover, such as your face, ears and hands. It’s important to choose a sunscreen that blocks both UVA and UVB light; some types of sunscreen only block UVB and not visible or UVA light. Titanium dioxide or zinc oxide-based reflectant sunscreens are best, as they will reflect some portion of visible light as well as both types of UV radiation.
The sun protection factor (SPF) written on your sunscreen tells you how protective it is, with higher numbers being better. Some types of sunscreen also have a star-based ranking system on the bottle, and are marked to a maximum of 4 stars, with 4 stars being the most protective.
You should apply sunscreen about 15 minutes before you go outside to give time to work.
Many people forget to put sunscreen on their lips — it’s a good idea to choose a lip balm that contains zinc or titanium oxide.
Light filtering through windows in your home can be a source of sun exposure and its problems. You may want to invest in a film that “tints” your windows to block harmful light. Amber films prevent most light that is harmful to porphyria patients.
In some regions, you can cover your car windows with film as well, but you should check with local authorities as to what level of tinting is acceptable. In the U.S., many states have specific limitations on tinting, so be sure to check before you bring your car in for this service.
Last updated: July 13, 2020
Porphyria News is strictly a news and information website about the disease. It does not provide medical advice, diagnosis, or treatment. This content is not intended to be a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding a medical condition. Never disregard professional medical advice or delay in seeking it because of something you have read on this website.
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