Consumers these days are being warned about the health hazards of highly processed foods. The message is that the health-conscious consumer should buy more whole foods and process them minimally. However, not all whole foods are safe, either, and some should come with a warning label. 

One of the most common problems caused by some fresh, natural foods are skin issues. Dermatitis can result from sensitivity and allergy to any food, or it can result from a food containing a chemical that makes your skin more sensitive to the sun.

Citrus fruits are notorious for causing dermatitis when exposing skin to fruit juice and peel. This includes oranges, lemons, grapefruit, and especially limes and bergamot. In fact, there is a disease called Lime Disease, (which is not the same as Lyme disease), which is caused by the blistering effect of lime juice on the skin when exposing the skin to the sun. It’s also called Margarita Disease, named after the drink that includes lime.

If you don’t want your skin to peel, then you don’t want to peel the skin of a citrus fruit when you are in the sun. 

What does sunshine have to do with it? 
The sun emits powerful ultraviolet light, which causes chemical reactions to occur. Ultraviolet light is a small part of the light spectrum coming from the sun, but when these wavelengths of light hit certain chemicals, the light energy is absorbed and a chemical bond is broken. This starts a cascade of reactions among unstable chemicals, ultimately result in skin damage. 

This is why you don’t want to leave out in the sun any fabric or plastic or other materials that can decompose under UV radiation. UV breaks down materials. This is also why you don’t want your skin to have too much sun. 

Keep in mind that all terrestrial life on Earth has evolved to live with solar radiation, and can heal from the damaging effects of UV.  In fact, plants and animals have evolved to use UV light for many necessary functions. In humans, for example, we need UV irradiating our skin to make Vitamin D. 

It is as though sunshine is an essential nutrient. But like all nutrients, there can be too much of a good thing.  

Plants, of course, have lots of chemicals, called phytochemicals, with the prefix phyto- meaning plant. Some of these phytochemicals are beneficial, such as vitamins, and are extracted from plants for their uses in medicine, perfumes, foods, cosmetics, and other products. But some of these plant chemicals are toxic, and these toxic chemicals can be in the same plant as the beneficial chemicals. 

In this case, the dangerous chemical is a furanocoumarin, which is a class of chemical compounds that are activated by UV light. Psoralen is the parent of this class of chemicals. 

Psoralen makes sunburn much more severe. If psoralen is on, or in, the skin, UV light from the sun activates the psoralen, making it highly reactive. This causes the psoralen molecule to bond with DNA in skin cells, which causes these cells to die. Symptoms of psoralen burning the skin include redness of the skin, edema, and blisters. 

UV rays can penetrate deep into the epidermis, into the dermis, so any psoralen on the skin, or in the skin, can be activated by the sun to make blister-forming eruptions. For some people, this also causes the skin to change color when healing, and can cause allergic or hypersensitivity reactions in other parts of the body with repeated exposure. 

The medical term for this problem is phytophotodermatitis, a word that literally means plant-sun-skin inflammation. It is not an allergic condition, since it does not require prior exposure. The blistering develops after about 24 hours of exposure, and peaks at 48-72 hours. It can take weeks to heal.

Skin reactions like this are a problem in farmers, grocers, and people who work with psoralen-containing foods. Of course, homemakers who cook for their families handle these daily. 

Unfortunately, lots of common, otherwise healthy foods have psoralen. This includes parsley, parsnips, carrots, and celery. Figs are also a problem, which can even cause skin blistering from simply touching the leaves or sap. Cloves are also high in psoralen. And all citrus fruit is high in psoralen, especially limes and bergamot. Bergamot oil is added to lots of drinks and other foods for flavoring, making these other foods also high in psoralen.

To give you an idea of what psoralen can do, consider its use in medicine to treat psoriasis eczema, and some other skin lesions, in a process called PUVA. This type of therapy is called photochemotherapy. Patients are given a psoralen drug, called methoxsalen, which within a short time is circulated throughout the body and into the skin. This gets the skin highly sensitive to UV rays, especially UVA, which is one of the UV wavelengths that goes deeply into the skin when you are in the sun. The patient is irradiated for up to 10 minutes over a series of treatments, essentially burning away the bad skin.

PUVA has been used for decades, and herbal remedies for skin ailments have included psoralen-containing plants being applied to the skin. However, there are side effects of this therapy. 

According to WebMD, “Psoralens can make your skin more sensitive to sunlight. They can raise your risk of sunburn, cataracts, and skin cancer. And your skin might age faster…Don’t eat limes, carrots, celery, figs, parsley, or parsnips while you take oral psoralens. It could boost the amount of natural psoralen in your system and make your skin even more sensitive to the sun.”

This means you are at risk of photosensitivity from eating foods containing psoralen, or applying those foods to your skin. This can lead to burns, skin cancer, and eye damage. 

Unfortunately, avoiding these foods will not make you safe from photosensitizers that you are consuming in medications. Some medications can directly be activated by UV to attack your skin when in the sun, as with psoralen. But other medications can cause damage to the skin by impairing the healing process. 

According to the North Carolina Department of Health and Human Services, “Certain food/drugs do not mix with ultraviolet light. Anyone taking any medication should consult with a physician PRIOR to tanning. Note: This is not a complete list of drugs or foods.” It then lists a frightening amount of drugs, including the most commonly used, which all make people more sensitive to sunlight and causing burns. 

This long list includes: 

Antihistamines

Anticonvulsants

Antifungals

Anti-inflammatory

drugs (Ibuprofen, Ketoprofen, Naproxen, etc.)

Antiseptics

Anitbiotics

Anticholesterol Medications

Antidepressants

Antipsychotic Medications

Artificial Sweeteners

Blood Pressure Medications

Coal Tar Productions (Tegrin, Denorex)

Oral Contraceptives & estrogen

Major Tranquilizers

Oral Diabetes meds

Sulphur based meds

Diuretics (fluid Pills)

Some Antimalarials –

Fansidar (a sulfa drug)

Chloroquine

Some deodorants

(perfumes colognes)

Cosmetics

Some herbal Products

Some Sunscreens

Tattoos

And the list goes on…

It also includes some foods:

Carrots

Celery

Citrus Fruits

Clover

Coumarin

Dill

Eggs

Figs

Garlic

Ginko Biloba

Grass (wheat, barley)

Lady’s Thumb (tea)

Lime oil

Mustards

Onions

Parsley

Parsnips (vegetables)

Saint John’s Wort

Smartweed (tea)

Vanilla oil

It is interesting that skin cancer is the leading type of cancer, and so many of these chemicals affect the skin and can cause cancer when in the sun. It’s not just the sun that harms the skin; it’s medications people take that increase the harm to the skin from the sun. 

Medications causing photosensitivity may be a reason why the medical industry has been encouraging people to wear sunscreen when in the sun, to minimize UV exposure. However, the sunscreen must be able to block UVA, which many do not unless they say “full spectrum”. However, even sunscreen lotions contain skin sensitizers, as the list above mentions. Ironically, this means sunscreen can possibly cause sunburns and skin cancer. 

According to a recent academic review, Drug‐induced photosensitivity: culprit drugs, potential mechanisms and clinical consequences:

“Drug‐induced photosensitivity, the development of phototoxic or photoallergic reactions due to pharmaceuticals and subsequent exposure to ultraviolet or visible light, is an adverse effect of growing interest. This is illustrated by the broad spectrum of recent investigations on the topic, ranging from molecular mechanisms and culprit drugs through epidemiological as well as public health related issues to long‐term photoaging and potential photocarcinogenic consequences…In total, 393 different drugs or drug compounds are reported to have a photosensitizing potential, although the level of evidence regarding their ability to induce photosensitive reactions varies markedly among these agents. The pharmaceuticals of interest belong to a wide variety of drug classes. The epidemiological risk associated with the use of photosensitizers is difficult to assess due to under‐reporting and geographical differences. However, the widespread use of photosensitizing drugs combined with the potential photocarcinogenic effects reported for several agents has major implications for health and safety and suggests a need for further research on the long‐term effects.”

These drugs and foods are common. If you are taking NSAIDS, such as aspirin, ibuprofen, or naproxen, you can more easily burn in the sun. The same goes for taking antibiotics, or antihistamines, or high blood pressure medication. Add to that having citrus or figs or a healthy salad or juice made of celery, parsley, and carrots, and you will be even more sensitive to the sun. Peel an orange at the beach or in the sunny park, and let the sunshine activate all the psoralen, and get ready for a few days of burned, blistered, red, hot, and damaged skin. 

This may also be why tanning is such a significant cause of skin cancer. The UV from these tanning treatments will be more damaging if you are priming your skin with psoralen from your diet or medications.  

If you want to keep the sunshine in your life, but want to minimize the risk of phytophotodermatitis from food, and chemophotodermatitis from medication, keep in mind the following:

1. Limit sun exposure to avoid peak sun intensity from 10 a.m. to 2 p.m. But don’t avoid the sun altogether. A little sun is necessary for health, including mental health. (Season Affect Disorder is from lack of sun.)

2. Wear loose-fitting, natural-fiber clothing when you want to block the sun from your skin. 

3. If you use sunscreen, make sure all the ingredients are safe. Look each ingredient up to see if it increases photosensitivity. Amazingly, many sunscreens contain chemicals that make your skin sensitive to the sun. 

4. Keep in mind that all chemicals on your skin will be irradiated with UV from the sun. This includes all lotions, creams, perfumes, and cleansers. Nobody is studying the many UV by-products from solar radiation of these chemicals, which then can get absorbed into your skin. 

5. When going out in the sun, remember the photosensitizing medications you are taking, and take precautions. 

6. Avoid foods that contain psoralen if you have any skin issues. 

7. Be cautious of foods that contain “natural flavors” or other unnamed natural ingredient, which could contain bergamot oil, or some other photosensitizing agent. 

8. Avoid tanning in a salon if you are on medications or eat foods that contain psoralen. 

9. Wash your hands well with soap and warm, not hot, water after handling any foods that contain psoralen. 

10. When preparing a picnic for a nice, sunny day at the park or beach, avoid UV-activated foods. 

11. Avoid tight clothing. This interferes with lymphatic circulation in the skin, which is essential for healing. After time in the sun, make sure your skin has proper circulation to allow the drainage of toxic, UV-irradiation chemical products. 

12. Keep in mind that, while the first skin contact exposure to psoralen and UV may result in blistering without an immune response, further exposure to these substances after that initial response may result in allergic reactions when taking that substance internally. This means the orange that you peeled at the beach in the sun which gave you blisters may now be giving you a rash when you eat citrus foods. The immune system learns to attack foods that cause dermatitis, and can generalize the attack, resulting in allergies to related foods. 

13. The phytophotodermatitis effect is directly related to sun exposure time and intensity, and photochemical concentration. The longer you are in the sun and the more intense the rays, the worse the skin burn. And the more foods you eat that contain psoralen, the worse the burn. 

14. If you develop a skin problem within 48 hours of tanning or of being in the sun, then look for causes in your diet or medications. 

15. Finally, discuss the need to avoid the sun with your healthcare provider. You may need Vitamin D supplementation. Or you may be able to use a different medication or treatment that doesn’t have to take the sunshine out of your life.