What Is Sun Allergy? Causes, Prevention & Treatment Tips

A sun allergy can pose a frustrating dilemma. When caught in the sun without protection, a sun allergy rash may emerge, leading to itchy, red, bumpy, and irritated skin.

Interestingly, the term “sun allergy” actually covers a broad range of types of sun allergies. So, what is a sun allergy exactly? In this article, we examine the causes behind a sun allergy and treatment strategies to help you cope.

What is sun allergy?  

A sun allergy, or sun rash, happens when the body has an allergic reaction to the sun. Many forms of sun allergies arise due to hypersensitivity or over-reactivity of the immune system.

Other types occur due to the combination of sun exposure and chemicals on the skin, such as sunscreen ingredients. In fact, many develop a child sun cream allergy within their early years, which looks very similar to a sun allergy rash.

Luckily, most forms of sun allergies are mild and very rarely life-threatening. At the same time, this does not mean a sun allergy skin rash is not annoying.

What does a sun allergy rash look like?

A sun allergy often appears within a few minutes to a few hours of being outside. It is usually itchy and may include bumps, hives, scaling, water blisters, or bleeding. Many people might notice a sun allergy on their hands at first or notice sun allergy bumps across their exposed skin. Exact symptoms may ultimately vary depending on the type of sun allergy you have (more on this below).

Heat rash or sun allergy, what’s the difference?

So, how can you tell the difference between a heat rash or sun allergy? Often, a heat rash may take more than a few minutes or hours to appear. It also tends to disappear fairly quickly, usually within a matter of days. Yet, a sun allergy, also called sun poisoning, appears almost immediately (or within a couple of hours) of being outside. It also may stick around for days or weeks, much to the dismay and irritation of the individual.

What causes sun allergy?

Unfortunately, experts do not entirely understand what causes a sun allergy. Some believe that genetics may play a role. Others suggest that the immune system may also be to blame. It’s also thought that certain medications or chemicals, such as those found in various sun protection brands, may lead to a sun allergy rash to arise.

What to expect if you have sun allergy

With a sun allergy, it does not take much for a rash to appear, with most cases noticing a rash appear within a matter of hours. Yet, it also does not take much to protect your skin from potentially irritating UV rays. Often, it will vary from individual to individual, as well as depend on the type of sun allergy and the severity of the rash.

For instance, the amount of skin exposed, the length of time in the sun, and the time of the day all play a part in the development of an allergic reaction. In some moderate to severe cases, headaches, light-headedness, shortness of breath, and life-threatening anaphylaxis may occur.

If a rash develops, there are also various treatment methods you can use to lessen your discomfort. Most sun rashes begin to disappear within a few hours, but some can stick around for days or weeks or get re-aggravated with repeated sun exposure. We explore sun allergy prevention and treatment in more detail in the later sections below.

Are there factors that make you more susceptible to sun allergy?

Certain risk factors can increase your odds of developing a sun allergy rash or experiencing sunscreen allergies, including:

• Using fragrant sunscreens or hygiene products or using sunscreens with specific chemicals in them (For example, some individuals are only allergic to certain types of sunscreen.)
• Taking specific medications, such as some antibiotics and pain relievers.
• Being previously diagnosed with another skin condition, such as dermatitis.
• Having a family member or a family history of sun or skin allergies.

When to see a doctor about your sun allergy?

It’s important to book an appointment with your family doctor if:

• You have an itchy rash that doesn’t go away or respond to any over-the-counter creams or medications.
• You experience chest pain, stomach pain, severe headaches, weakness, vomiting, difficulty breathing, trouble swallowing, or muscle cramps. If this happens, you may need to seek out immediate, emergency care.
• You have a rash that covers a large area of the body, even parts that were covered from the sun.
• You have abnormal bleeding that occurs alongside a rash.

Questions to expect from your doctor about your sun allergy

For diagnosing a sun allergy, your doctor may perform a patch test to determine if a reaction occurs or UV testing, also called photo testing, to determine if the skin reacts to UV rays. Blood and skin samples may also be taken; These may help eliminate skin cancer as an issue in certain cases.

From there, your doctor may inquire about your rash and symptoms using the following questions:

• What does the affected skin look like?
• What areas are affected?
• What symptoms are you experiencing?
• How long do your symptoms typically last?
• Do you have similar reactions when exposed to sunlight through glass?
• Do you have a family history or relative with a sun allergy?
• What suncare or beauty products do you apply to your skin?
• Have you had reactions to sunscreen before?

The answers to these questions help your doctor determine a proper diagnosis and the next steps.

Types of sun allergy

The most common types of sun allergy include:

• Polymorphous light eruption (PMLE): With this type of sun allergy, hardening of the skin may develop after repeated exposure. This usually happens in the spring and summer months, and it’s more common in women. The rash (which often appears as dry, itchy blisters or patches) that coincides with this often goes away within a couple of days, as long as there is no further exposure to the sun.

• Actinic prurigo (hereditary PMLE): This is a genetic condition that causes the skin to become more sensitive to UV rays. These rashes can last a few hours to a few days, as well as spread to skin that was not directly exposed to the sun.

• Photoallergic eruption: This type of sun allergy occurs when certain chemicals on the skin are exposed to the sun, leading to rashes and blisters.

• Solar urticaria: Specifically, this type of allergy will form hives or red bumps, often just within minutes of sun exposure. Yet, they often disappear within about half an hour to a couple of hours, as long as there is no re-exposure in this timeframe. This is one of the most common forms of sun allergy and occurs across a wide range of people.

How is solar urticaria diagnosed?

Solar urticaria is usually diagnosed using the phototesting method, where the skin is exposed to different wavelengths and UV rays found in sunlight. Usually, your doctor will recommend this type of testing after determining that your rash is similar to what is experienced with solar urticaria (usually meaning it appears within minutes of being outside but disappears within hours of being inside and doesn’t include blisters or hives).