Managing Photosensitivity With Erythropoietic Protoporphyria (EPP)

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Photosensitivity is a medical term for sensitivity to ultraviolet (UV) light that comes from the sun or another light source. It is sometimes referred to as being allergic to the sun.

There are many causes of photosensitivity, such as reactions to certain medications and underlying health conditions. One such condition is erythropoietic protoporphyria (EPP), which is a rare genetic disorder. People with EPP experience a range of photosensitivity, from mild discomfort to severe pain.

This article looks at photosensitivity related to EPP, including facts about the condition and how sun sensitivity can be managed.

Woman practicing sun protection

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Facts About EPP Disease and Porphyrias

Erythropoietic protoporphyria (EPP) is a type of genetic disease called porphyria. People with EPP have decreased activity of an enzyme called ferrochelatase in their red blood cells. This leads to a buildup of a protein called protoporphyrin that can make their skin very sensitive to sunlight.

EPP is most often caused by a mutation in the ferrochelatase (FECH) gene, which, in turn, diminishes the activity of an enzyme needed to make heme heme (forerunner to hemoglobin, which transports oxygen in the blood). Less frequently, those with EPP have mutations in a different gene, ALAS2. This condition is called X-linked protoporphyria (XLP), and can only be passed to children by the mother.

The mutations in the FECH gene are passed down in an autosomal recessive pattern. This means that one parent has a very strong mutation and the other has a weaker one. If a child receives both mutations, the stronger mutation dominates the weaker one and they will develop symptoms.

People who inherit only one mutation usually don't develop symptoms, but they can be a carrier, meaning they can pass down the mutation to their child.

Because EPP is a rare condition, it can be difficult to diagnose. A healthcare professional would consider a patient’s medical history and symptoms, conduct a physical exam, and perform lab tests to determine if that person has EPP.

Enzyme Deficiency and Skin Health

There are eight different enzymes involved in making heme. Mutations to the FECH gene inhibit the activity of an enzyme called ferrochelatase needed to make heme. As a result, a substance called protoporphyrin builds up in certain parts of the body, including bone marrow, blood, skin, and the liver.

The buildup of protoporphyrin in the skin can cause intense sensitivity to sunlight, also known as photosensitivity. This can cause people with EPP to experience tingling, itching, or burning of the skin when exposed to the sun.

For someone with EPP, keeping the pain away during flare-ups may mean that they avoid sunlight or anything that emits UV light. This can significantly impact everyday life.

Symptoms of Photosensitivity

The most common symptom of EPP is photosensitivity. Approximately 80%–99% of people with EPP experience photosensitivity as well as itching and redness or inflammation of the skin (erythema).

Other less common symptoms include: 

  • Gallstones (hard bile deposits in the gallbladder)
  • Elevated liver enzymes or other liver problems
  • Eczema (atopic dermatitis, causing itchy, red skin)
  • Fluid under the affected area (edema)

What Sun Sensitivity Looks Like

Usually, photosensitivity will show up as redness on the skin; there might also be fluid underneath the skin. Sometimes blisters or scars may appear on the affected area if the skin is exposed to sunlight for a long time, but this is rare and usually not severe.

What Sun Sensitivity Feels Like

For people with EPP, photosensitivity from exposure to the sun can range from mild enough to be a nuisance to so severe that it impacts daily life. Warning signs upon exposure include tingling, itching, and burning of the skin. Longer sun exposure can lead to increasing pain. 

The pain is usually in the face, hands, and arms, likely because these are parts of the body that are more often exposed to sunlight. Sometimes the pain is so severe that someone with EPP may need to avoid any UV-emitting sources like some light bulbs. The pain usually subsides within 24 hours. 

Consulting With a Specialist

Sometimes symptoms of EPP aren’t severe enough to make someone think to see a healthcare professional about it. However, symptoms like pain, tingling, or burning upon exposure to sunlight are indicators that it’s time to seek medical attention.

You may even experience photosensitivity when sitting by a window, including in the car, with sunlight coming in. If you are avoiding sunlight because of such discomfort, it is best to speak with a healthcare professional. 


While symptoms usually start in childhood, EPP is not always diagnosed right away. While EPP symptoms are distinct, young children—and especially babies—won’t always have the words to describe the pain from sun exposure. Blistering and fluid under the affected area are also uncommon, so there aren't usually physical changes for a parent to notice and address.

In other words, unless a child can describe the characteristic pain associated with EPP, it may go undiagnosed. However, if sensitivity to sunlight is suspected, a healthcare provider can do a clinical evaluation, which could include seeing if enough protoporphyrin has accumulated to be detected in a lab test. 


Symptoms like skin redness or itching may go overlooked as they may be seen as temporary reactions to the sun or an allergic reaction to something like clothing material. However, if these symptoms are consistently present upon being exposed to sunlight, talk to a healthcare professional.

If EPP is suspected, a healthcare provider can order lab tests to see if there are high levels of protoporphyrin in the blood. This would help them diagnose EPP. Experienced biochemistry labs can usually distinguish EPP from XLP based on the type of protoporphyrins in the blood.

Furthermore, because EPP and XLP are related to genetic mutations, genetic testing and counseling can confirm diagnosis and encourage genetic counseling and testing of family members.

How EPP Is Treated

Sun protection is vital for people with EPP. It is the main form of treatment for managing EPP. Some artificial lights, like fluorescent lights, may also need to be avoided to manage EPP flare-ups. 

Medication is also available to treat EPP. In 2019, the Food and Drug Administration (FDA) approved the prescription drug Scenesse (afamelanotide) for adults with EPP. This medication works to improve tolerance to the sun and light by increasing levels of eumelanin, a compound that protects against UV radiation from light.


Supplements are often recommended to be used as part of EPP management, including:

  • Vitamin D to make up for deficiencies due to lack of sun exposure
  • Iron, if iron deficiencies are detected in blood tests
  • Beta carotene to improve tolerance to sunlight

While supplements can be purchased over the counter, it is always best to speak with a healthcare professional before taking supplements to treat or manage any condition, including EPP.

Adapting to Sun Sensitivity

Being extremely sensitive to the sun impacts everyday life. Avoiding sunlight or even artificial lights can mean lost opportunities to socialize with friends or mental exhaustion from having to think through how to protect yourself from flare-ups when out and about. 

While there is no cure for EPP yet, it is treatable. Drugs like Scenesse can significantly help someone living with EPP. However, it may not be accessible to everyone with EPP. Even with medication, living with EPP and the associated sun sensitivity may mean making a lot of creative adaptations to be comfortable.

At-Home Sun Safety

Here are some steps you can take to adapt your home to be more photosensitive aware:

  • Get the right light bulbs: LEDs and incandescent bulbs emit almost no UV.
  • Put up sun-blocking curtains: Using heavy curtains reduces sun exposure from windows.
  • Wear skin-covering clothes: Wearing long sleeves and pants can help reduce the amount of skin being exposed to light even while at home.

Sun Safety Away From Home

When not in your home, it can be harder to control your exposure to the sun. However, when out and about, the following few essentials can help keep you safe and comfortable:

  • Clothing, like long sleeves, pants, and gloves
  • Hats
  • Sunglasses
  • Sunscreen
  • Tinted windows in vehicles


Photosensitivity is when the skin is extremely sensitive to UV light coming from the sun or another light source. It is associated with the condition EPP and can cause mild to severe pain upon sun exposure. Managing photosensitivity from EPP includes lifestyle changes, medication, and supplements.

A Word From Verywell

While EPP is not yet curable, photosensitivity from EPP is manageable. But management is an everyday task and being on constant alert for possible sun exposure can affect mental health.

It can help to remember that you are never alone in your struggle. While you are layering clothes to cover every inch of skin possible before leaving the house, someone else is drawing their sun-blocking curtains.

Take care of yourself by being mindful of your needs and seeking your healthcare provider's advice on managing your symptoms effectively, so that you have the resources you need to make day-to-day life easier.

Frequently Asked Questions

  • What are the first photosensitivity symptoms of EPP?

    Pain, itching, and burning of the skin after exposure to sunlight or some types of artificial light, such as fluorescent light, are some of the first signs of hypersensitivity to sun due to EPP.

  • What can parents do to help a child with EPP?

    Some ways a parent can help a child with EPP include making sure playdates are indoors, going to kid-friendly indoor exercise venues, and considering homeschooling so that you can control the light environment.

  • Do people with skin porphyria always experience photosensitivity?

    Generally, yes. People with skin porphyria usually experience itching, swelling, and blistering of the skin when it is exposed to sunlight.

  • What does photosensitivity feel like for EPP patients?

    Photosensitivity can range from mild to severe. Upon exposure to the sun, signs of photosensitivity include tingling, itching, and burning of the skin. Longer sun exposure can lead to increasing pain, but it usually goes away within 24 hours.

6 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. National Organization for Rare Disorders. Erythropoietic protoporphyria and X-linked protoporphyria.

  2. Porphyria Foundation. Erythropoietic protoporphyria (EPP) and X-linked protoporphyria (XLP).

  3. National Institute of Health. Autosomal erythropoietic protoporphyria.

  4. Heerfordt IM, Lerche CM, Philipsen PA, Wulf HC. The effect of vitamin D recommendations on serum 25-hydroxyvitamin D level in patients with erythropoietic protoporphyriaNutrition. 2022;93:111477. doi:10.1016/j.nut.2021.111477

  5. Balić A, Mokos M. Do we utilize our knowledge of the skin protective effects of carotenoids enough?Antioxidants (Basel). 2019;8(8):259. doi:10.3390/antiox8080259

  6. MedlinePlus. Porphyria.

By Emily Brown, MPH
Emily is a health communication consultant, writer, and editor at EVR Creative, specializing in public health research and health promotion. With a scientific background and a passion for creative writing, her work illustrates the value of evidence-based information and creativity in advancing public health.