Understanding Photosensitivity: What Foods Cause Photosensitivity?

October 5, 2025 •

4 min read

An estimated one in ten people will experience a phototoxic skin reaction in their lifetime, and certain foods are surprising triggers. Known as phytophotodermatitis, this condition occurs when photosensitizing chemicals in specific plants, fruits, and herbs react with sunlight, leading to a burn-like rash.

Quick Summary

Certain foods contain photosensitizing compounds like furanocoumarins, which can trigger adverse skin reactions when exposed to UV light. These include common items like citrus fruits, celery, and parsley, and can lead to painful rashes or blisters.

Key Points

Furanocoumarins are the culprits: These natural plant chemicals, such as psoralens, are the primary cause of food-induced photosensitivity.
Citrus can cause 'margarita dermatitis': Contact with lime or lemon juice on the skin followed by sun exposure can lead to blistering phytophotodermatitis.
Celery and other vegetables are triggers: Members of the carrot family, including celery, parsnips, and carrots, contain photosensitizing compounds.
Herbs and supplements pose a risk: Certain herbs like dill, parsley, and St. John's Wort can increase your skin's sun sensitivity.
Prevention is key: Washing your hands thoroughly after handling these foods and being mindful of spills in the sun can prevent reactions.

While many people are aware of the risks of sun exposure, few realize that their diet can play a significant role in increasing their skin's vulnerability to UV rays. Photosensitivity, or heightened sun sensitivity, can be triggered by medications, cosmetics, and certain foods. The key culprits in food-induced photosensitivity are natural organic chemicals known as furanocoumarins, including compounds like psoralens. When these substances are ingested or come into contact with the skin and are subsequently exposed to sunlight, they can cause a severe inflammatory reaction.

The Culprits: Foods Containing Photosensitizing Compounds

Citrus Fruits

Citrus fruits, particularly limes, lemons, and grapefruits, are well-known triggers for a localized form of photosensitivity called 'margarita dermatitis' or phytophotodermatitis. The furanocoumarins are concentrated in the peel and juice of these fruits.

Limes and lemons: The psoralens in their juice are a primary cause of contact dermatitis. The phrase 'margarita burn' comes from the common scenario of lime juice splashing onto the skin while making cocktails and causing a blistering rash after sun exposure.
Grapefruit: Studies have shown that consuming large amounts of citrus, including grapefruit, may increase melanoma risk, though findings remain inconsistent and controversial.

Celery and Root Vegetables

Several members of the Apiaceae family, which includes celery, carrots, and parsnips, are rich in furanocoumarins.

Celery: High levels of psoralens, especially in raw celery stalks, have been linked to phototoxic reactions. Contact with celery juice or handling large quantities, as seen in farmworkers, can result in severe skin inflammation upon sun exposure.
Parsnips and Carrots: Wild parsnips contain high levels of photosensitizing agents, and wild carrots and cultivated varieties also possess these compounds.

Herbs and Spices

Several herbs and spices are natural photosensitizers, especially when applied topically or consumed in concentrated amounts.

Dill and Fennel: These herbs contain furanocoumarins that can cause photosensitivity.
Parsley and Coriander: Both fresh and dried versions of these herbs can increase sun sensitivity.
Cumin: This spice is another member of the Apiaceae family that contains photosensitizing compounds.

Herbal Supplements

St. John's Wort: This herbal remedy, often taken for depression, is known to cause photosensitivity due to the compound hypericin. Oral ingestion is the primary concern, and it is advised for photosensitive individuals to avoid it, especially in combination with UV therapy.

The Mechanism Behind Food-Induced Photosensitivity

There are two main ways food can cause photosensitivity:

Phototoxicity: This is the more common reaction, occurring when photosensitizing chemicals (like furanocoumarins) are absorbed by the skin. When UV light hits the skin, it activates these chemicals, causing direct damage to skin cells and leading to a rapid, exaggerated sunburn. This reaction is dose-dependent, meaning more of the chemical and more sun exposure will result in a more severe reaction. Phytophotodermatitis from citrus juice is a classic example.
Photoallergy: This is an immune-mediated response where the photosensitizing agent is structurally changed by UV light, becoming an allergen. This triggers an allergic reaction in the skin that can appear as a rash or inflammation and is not dose-dependent. It is less common with foods but can occur with certain medications and topical agents.

Comparison of Common Photosensitive Foods


Food Category	Specific Examples	Photosensitizing Compound	Typical Reaction Type	Risk Level
Citrus	Limes, Lemons, Grapefruits	Furanocoumarins (Psoralens, Bergapten)	Topical (Contact)	High (when handled in sun)
Root Vegetables	Celery, Parsnips, Carrots	Furanocoumarins (Psoralens, Bergapten)	Both Topical and Systemic	Moderate to High
Herbs & Spices	Parsley, Dill, Fennel, Coriander, Cumin	Furanocoumarins (Psoralens)	Both Topical and Systemic	Moderate
Herbal Supplements	St. John's Wort	Hypericin	Systemic	High (especially with oral use)

How to Avoid Food-Induced Photosensitivity

Fortunately, avoiding photosensitive reactions from food is manageable. Here are some preventative steps:

Wash thoroughly after handling: After preparing citrus fruits, celery, or parsley, wash your hands and any other exposed skin with soap and warm water.
Be mindful outdoors: When enjoying a sunny day, be careful with food and drinks that contain photosensitizing ingredients. Spilled lime juice from a drink or handling lemons for a dish can cause a delayed reaction.
Consider your diet and sun exposure: If you know you are sensitive to sunlight, you might consider moderating your intake of foods high in furanocoumarins during peak sun exposure periods.
Talk to your doctor about supplements: If you take St. John's Wort or other herbal supplements, discuss the photosensitivity risk with a healthcare professional.
Protect yourself proactively: Always wear broad-spectrum sunscreen with an SPF of 30 or higher and protective clothing, especially if you have highly sensitive skin or are knowingly exposed to photosensitizing agents.

Conclusion

What foods cause photosensitivity is a topic of importance for anyone who spends time outdoors, especially those with sensitive skin. While most people can enjoy these foods without issue, those who are particularly susceptible to sun damage, or who spend a lot of time in the sun while preparing food, should be aware of the risks. By understanding which common dietary items contain photosensitizing compounds like furanocoumarins and taking simple precautions like washing your hands and protecting your skin, you can significantly reduce your risk of painful and unsightly reactions. If you suspect a reaction, seeking professional medical advice is always the best course of action.

For more detailed information on specific photosensitizing compounds and their effects, you can refer to authoritative sources such as the National Institutes of Health.

Frequently Asked Questions

Photosensitivity caused by food, often called phytophotodermatitis, is a skin reaction that occurs when chemicals from certain plants and foods interact with UV light from the sun, causing inflammation and a severe, burn-like rash.

Yes, touching or squeezing lemons and limes, especially in direct sunlight, is a common cause of phytophotodermatitis. The furanocoumarins in the fruit's juice can cause a reaction if they remain on your skin when exposed to UV light.

Generally, yes. For most people, a photosensitive reaction only occurs when photosensitizing chemicals are on the skin or have been ingested in very high amounts shortly before significant sun exposure. Eating these foods as part of a regular diet in a controlled environment is usually safe.

The reaction can appear within 24 to 48 hours after sun exposure and can last for several days or weeks, depending on the severity. In some cases, it can cause long-lasting skin discoloration.

For mild reactions, applying a cool, wet cloth to the affected area can be soothing. For more severe cases with blistering or persistent pain, it is best to consult a doctor or dermatologist for treatment.

Photosensitizing compounds are found in the natural plant form. While processed foods containing these plants could theoretically be a factor, the concentration is often lower. However, some products containing 'natural flavors' might include trace amounts of photosensitizing agents, so it's best to be cautious if you are highly sensitive.

All carrots contain some furanocoumarins, but the concentration is much lower in cultivated varieties than in wild carrots. The risk of a reaction from casual consumption is very low, but contact with the plant's sap, especially from wild varieties, can be a trigger.