What is a sun allergy? Learn about photosensitivity

People often feel better and happier when the sun is shining. But, for people with photosensitivity, sunlight causes health problems. Photosensitivity, also called sun allergy or photodermatoses, is an extreme sensitivity to ultraviolet radiation (UV rays) from light sources like sun exposure or tanning beds. There are several types of sun allergies. However, all types increase the risk of damage to your skin and your chance of developing skin cancer. The causes of photosensitivity include medical conditions, medications, and genetics. 

What is a sun allergy?

An allergy occurs when your immune system reacts to a foreign substance, such as pet dander or pollen, causing inflammation and other symptoms. When you have a sun allergy, skin damage from UVA and UVB rays is recognized as a foreign substance. It triggers your immune system, resulting in itchy rashes, redness, and inflammation on sun-exposed skin. You are most likely to see a photosensitivity reaction on your neck, back of hands, outside of arms, and lower legs, according to Harvard Health. In severe cases, symptoms can spread to areas of the body not exposed to UV light. They might appear within minutes of being in the sun or several days later. 

Types of photosensitivity
Skin condition	Cause	Common	At-risk populations	Age of onset	Symptoms	Incubation period
Polymorphous light eruption (PMLE)—AKA phototoxicity or sun poisoning	Most commonly drug-induced	Most common; affects 10%-15% of U.S. population	Affects more women than men	Teens to 20s	Itchy rash, blisters, small red areas, flu-like symptoms, headache, fever, chills, nausea	Within a minutes to hours after UV exposure
Photoallergy	Drug-induced	Less prevalent than phototoxic reactions	People who use certain topical medications, cosmetics, and fragrances	All ages	Burning or itchy rash and blisters	24-72 hours after exposure to drug and light
Actinic prurigo	Genetic	Rare	Affects more American Indians than other races, affects more women than  men	Usually before age 10	Itchy, crusty bumps on face, neck, upper extremities, and buttocks	Typically occurs in spring and can last through winter
Solar urticaria	Unknown	Rare; only 7% of sun allergies	Most prevalent in women	Median age of onset is 35	Hives, burning, stinging. Skin can appear darker after the reaction.	Anywhere from a few hours to a few weeks

What causes photosensitivity?

There are several known causes for sun sensitivity, including drug-induced photosensitivity, a symptom of a medical condition, genetics, or it can be idiopathic, meaning the cause is unknown. 

Sun allergies often first appear in childhood, but it very much depends on the type and cause. “Some people can become sun-sensitive and develop an allergy to sun exposure as teens or adults,” explains Vindhya Veerula, MD, a board-certified dermatologist in Fort Wayne, Indiana. “This could happen on its own or in conjunction with an autoimmune disorder. Lupus is a common cause of sun sensitivity. Sometimes exposure to certain plants or other chemicals activate with UV radiation and can cause sensitivity.” 

Photosensitive drugs list

Some medications that might cause sun sensitivity, including acne medications containing alpha-hydroxy acids, antibiotics (i.e. tetracycline and doxycycline), allergy medicine, blood pressure meds such as hydrochlorothiazide, nonsteroidal anti-inflammatory drugs (NSAIDs) like ibuprofen or naproxen, and even some vitamins and supplements, including St. John’s wort. You can find a full list of sun-sensitizing medications here. 

When prescribed a new medication, it is vital to read the potential side effects, discuss preventative measures you can take to avoid adverse skin reactions, and understand when to contact a medical professional. 

Diseases that cause sun sensitivity

Some medical conditions that cause photosensitivity, according to the Skin Cancer Foundation, include:

• Actinic folliculitis
• Bloom syndrome
• Chronic actinic dermatitis
• Darier’s disease
• Dermatomyositis
• Disseminated superficial actinic porokeratosis
• Hydroa vacciniforme
• Idiopathic photodermatoses
• Lichen planus actinicus
• Systemic lupus erythematosus
• Pellagra
• Pemphigus
• Porphyria
• Pseudoporphyria
• Psoriasis
• Rosacea
• Rothmund-Thomson syndrome
• Xeroderma pigmentosum

Also, a deficiency in niacin (a form of vitamin B3) known as pellagra, can contribute to photosensitivity, according to Penn State Hershey Medical Center. 

Sun allergy treatment tips

“Treatment might start with a thorough history and physical exam, along with bloodwork and a skin biopsy, if necessary,” says Dr. Veerula. “Often it is treated by avoiding the trigger, which in this case is UV rays, from the sun or tanning beds. Usually, topical and oral anti-inflammatories can help.”

Prevention

The best treatment for sun sensitivity is prevention. Using proper sun protection methods significantly reduce uncomfortable or painful symptoms. Dermatologists recommend that everyone should use a broad-spectrum sunscreen with an SPF of 30 or higher. People who experience symptoms almost immediately after being in the sun should take steps to avoid direct sunlight.

RELATED: Does sunscreen expire?

Some commercial products, like Eucerin Sun Allergy Protect Gel Cream, indicate they can reduce sun allergy symptoms and protect your skin against skin cancer-causing antioxidants. However, you should speak with your doctor before relying on them to protect yourself when out in the sun.

Sunburn relief

Despite taking the proper steps to protect your skin, you could still experience photoallergic reactions. For severe sunburns, the American Academy of Dermatology suggests the following at-home treatments:

• Stay out of the sun and wear protective clothing
• Take frequent cool showers or baths or apply cold compresses
• Liberally apply moisturizers containing aloe or soy
• Moisturize affected areas with coconut oil to prevent skin from peeling
• Use ibuprofen to relieve swelling and discomfort if necessary
• Drink extra water
• Antihistamines and over-the-counter cortisone creams reduce symptoms that often accompany the healing process

When to see a doctor for an allergic reaction to sun

The following symptoms should prompt a call to your doctor or a visit to a medical professional: 

• Abnormal bleeding under the skin
• A rash on parts of your body not exposed to the sun
• A rash that doesn’t respond to over-the-counter medicine
• Blisters (A blistering sunburn is considered a 2nd-degree burn, and you should seek medical attention)
• Dehydration (decreased amount of urine, dry mouth, swollen tongue, fatigue, sugar cravings, confusion, dizziness, heart palpitations)
• Flu-like symptoms
• Fever with chills
• Headache
• Heat exhaustion (excessive sweating, rapid or weak pulse, nausea, vomiting, muscle cramps, fatigue, weakness, dizziness, headache, fainting)
• Heatstroke (fever, fast heartbeat, headache, dizziness, confusion, nausea, fainting)
• Nausea
• Weakness

Resources:

• Sun allergy: Symptoms, causes, treatments, Cleveland Clinic
• Are you allergic to the sun?, Wexner Medical Center
• Actinic prurigo, StatPearls
• Solar urticaria, StatPearls
• Warning signs and symptoms of heat-related illness, CDC