Month: December 2021

No one is truly allergic to the sun, but some people are quite sensitive to different types of sun rays and may develop mild to serious reactions after spending time in the sun.

There are several types of “sun allergies,” but polymorphous light eruption (PMLE), an autoimmune condition in the skin that occurs after sun exposure, is one of the most common. Other conditions considered as sun allergies are solar urticaria (hives and reddish patches that usually start 30 minutes to two hours after the sun exposure), actinic prurigo (papules and nodules that are intensely itchy on sun-exposed skin areas), and photoallergic reaction (when the UV rays from the sun modify the chemical structure of medications or products applied to the skin, and a person develops an allergy to the newly modified substance).

What causes PMLE?

People who have PMLE have immune cells that are triggered by sun rays, which attack their skin, and they develop a skin reaction to the sun’s the ultraviolet (UV) rays.

PMLE represents 70% of all sun-induced skin eruptions. It can affect both sexes and all skin types, and it usually starts when someone is a teen or young adult. PMLE may be an inherited condition. Being a female, having fair skin, and living in the north are other risk factors.

PMLE is more common in young women who live in temperate climates. People who live in temperate climates spend all winter out of the sun, so when it becomes warmer the sun exposure is intense. People who live in warmer climates are desensitized because they have a higher sun exposure all year.

What does PMLE look like?

PMLE can appear several hours or days after the first major sunlight exposure of the season, usually during spring or at the beginning of summer. The areas of the body generally affected the most are the ones that are covered during wintertime, but not in the summer: the neck, the chest, and the outer parts of the arms.

After exposure to the sun, people with PMLE usually notice reddish patches on their skin. These spots may itch, burn, or sting, but they typically don’t leave a scar. In more severe cases, the patches cover most of the body and may also be associated with headaches, fevers, tiredness, and low blood pressure. (If you experience these symptoms, see an urgent care provider for evaluation.) If you think you have PMLE or another sun allergy, a dermatologist is the best doctor to evaluate and treat your skin condition.

Does PMLE get better?

PMLE lesions often get better in approximately 10 days, and it’s important to avoid sun exposure until you are healed. People who develop PMLE can experience significant discomfort and have their life negatively impacted during the spring and summer months. However, repetitive sun exposure can make PMLE less likely to occur. The hardening effect, as it is called, means that the skin lesions that appear after the first episode are less severe, and they can be better tolerated during subsequent episodes.

What are current treatments for any sun allergy, including PMLE?

The best treatment is to prevent sun exposure. Avoid sunlight when it is most intense (from 10 a.m. to 4 p.m.), and use UV-protecting clothing or clothes made of darker and thicker fabrics, as they will prevent the UV rays coming from the sun from reaching your skin. Hats with a wide brim protect your scalp, face, and (partially) the neck.

Broad-spectrum sunscreens that protect your skin from both UVA and UVB rays should be used daily, even if it’s cloudy. Apply sunscreen on your face and any part of your skin that is not covered by a hat or clothing. Reapply sunscreen every two hours, and if you go swimming or get sweaty reapply more frequently (water-resistant sunscreen should also be reapplied).

If you develop PMLE, the areas of skin impacted can be treated with steroid creams. In severe cases, your doctor may recommend a short course of steroid pills. Medications that reduce the immune response, such as azathioprine, are options for treating PMLE, since it is an autoimmune condition (the body is attacking it is own healthy cells).

Antihistamines are medications typically used for allergies that may help shorten the duration of reddish patches that itch or burn, and they also reduce inflammation.

Hydroxychloroquine (a medication also used to treat malaria) can be used in case of flare-ups, or as a prevention method when people travel to sunny locations during winter vacations.

Oral Polypodium leucotomos extract, a natural substance derived from tropical fern leaves, may work as a potent antioxidant, and has anti-inflammatory properties that are beneficial in the prevention of PMLE. Other nutritional supplements containing lycopene and beta-carotene (vitamin A derivatives) have a similar effect. A dermatologist will guide you on the best way to use these medications.

The bottom line

Sun allergies are common in temperate climates, but with a dermatologist’s guidance, vigilant sun prevention, and medications they can be managed throughout the sunny months of the year.

About the Authors

Neera Nathan, MD, MSHS, Contributor

Dr. Neera Nathan is a dermatologist and researcher at Massachusetts General Hospital and Lahey Hospital and Medical Center. Her clinical and research interests include dermatologic surgery, cosmetic dermatology, and laser medicine. She is part of the … See Full Bio View all posts by Neera Nathan, MD, MSHS

Lais Lopes Almeida Gomes, Contributor

Dr. Lais Lopes Almeida Gomes is a dermatology research fellow at Massachusetts General Hospital, and a pediatric dermatologist in Brazil. Her clinical and research interests include atopic dermatitis and global health. She is part of the … See Full Bio View all posts by Lais Lopes Almeida Gomes

A study asks whether people who eat a lot of fish have a higher risk for the skin cancer melanoma.

If you’re trying to stick to a healthy diet, fish is a good choice, right? After all, fish is high in protein, low in saturated fat, and a good source of omega-3 fatty acids, vitamin D, and many other nutrients. Eating more fish can mean eating less of foods with harmful fats and higher calorie counts. Indeed, nutritionists commonly recommend more seafood (and fewer cheeseburgers) to improve your diet, and nutrition guidelines promote fish as part of a healthy diet.

So, it seems surprising that a new study in Cancer Causes and Control suggests a link between eating fish and skin cancer, particularly since the biggest known risk factor for melanoma is not dietary ­–– it’s sun exposure. Having five or more sunburns in your life doubles your risk of developing melanoma.

A study links eating fish often with higher risk of melanoma

Melanoma, the most serious type of skin cancer, is responsible for more than 7,500 deaths in the US each year. And cases are on the rise.

In the new study, researchers found a higher risk of melanoma among people who ate the most fish. This study is among the largest and most well-designed to examine this link. Nearly 500,000 people in six US states completed a dietary questionnaire in 1995 or 1996. The average age of participants was 61 and 60% were male. More than 90% were white, 4% were Black, and 2% were Hispanic.

Over the following 15 years, the researchers tallied how many people developed melanoma, and found that:

• The rate of melanoma was 22% higher among people reporting eating the most fish (about 2.6 servings per week) compared with those who ate the least (0.2 servings a week, or about one serving every five weeks). Similar trends were noted for intake of tuna.
• The risk of precancerous skin changes (called melanoma in situ) rose similarly among those in the group that ate the most fish.
• Interestingly, researchers found no increased risk of melanoma among those eating the most fried fish. This is surprising because, if eating fish increases the risk of melanoma as the study suggests, it’s not clear why frying the fish would eliminate the risk.

Does this mean eating fish causes melanoma?

No, it doesn’t. It’s too soon to make definitive conclusions about the relationship between fish in our diets and melanoma. The study had important limitations, including

• Type of study. Observational studies like this one can detect a possible link between diet and cancer but cannot prove it.
• Reliance on self-reported survey data. People self-reported how many servings of fish they ate each week, which may not be accurate. Also, researchers assumed that fish consumption reported on the initial survey persisted for 15 years, which may not have been the case.
• Accounting for other factors. Many factors affect risk for melanoma, such as varied sun exposure depending on where participants lived. The analysis did account for some key factors, yet the study didn’t collect information about sun exposure, past sunburns, or use of sunscreen — all important in melanoma risk. Nor did researchers ask about skin type or number of moles; fair skin or higher numbers of moles raise risk for melanoma.
• Contaminants. Mercury or arsenic in fish may be to blame for its link to melanoma. This study did not record contaminants, but previous studies link mercury exposure with the risk of skin cancers, including melanoma.
• Lack of diversity. It’s not clear if the findings apply broadly to people in different racial and ethnic groups, because nine in 10 study participants were white.

Are some fish safer to eat than others?

The study did not explore this question. However, if contaminants like mercury in fish are responsible for increasing the risk of melanoma, the FDA offers advice on which fish are safer to eat, particularly for children and those who are pregnant or breastfeeding.

Yet even if fish is confirmed as a contributor to the risk of melanoma, other positive effects of fish consumption (such as cardiovascular benefit) may far outweigh this risk.

The bottom line

The researchers responsible for this study are not recommending a change in how much fish people eat. More study is required to confirm the findings, investigate which types of fish affect melanoma risk, and determine whether certain contaminants in fish are responsible for any added risk.

In the meantime, fish with lower mercury levels (such as salmon and clams) remain better dietary choices than the high-fat, highly processed foods typical of many Western diets.

If you’re planning to spend a lot of time outside this summer, limiting sun exposure and using sunscreen will likely have a bigger impact on skin health and your overall health than avoiding seafood.

About the Author

Robert H. Shmerling, MD, Senior Faculty Editor, Harvard Health Publishing

Dr. Robert H. Shmerling is the former clinical chief of the division of rheumatology at Beth Israel Deaconess Medical Center (BIDMC), and is a current member of the corresponding faculty in medicine at Harvard Medical School. … See Full Bio View all posts by Robert H. Shmerling, MD