June 2024

Extra Sunscreen Needed: Photosensitizing Ingredients

The summer months are upon us. Just like some medications, certain supplements can increase sun sensitivity. This is a good time to remind patients to use extra sun protection – particularly if they use alpha hydroxy acids (AHAs), bergamot, or St. John’s wort.

AHAs are a group of natural acids found in foods, including citric acid, glycolic acid, lactic acid, malic acid, and tartaric acid. They’re commonly used in topical anti-aging products, with glycolic acid having the strongest evidence of benefit – applying glycolic acid to the skin seems to reduce wrinkles and other signs of aging. But like all AHAs, it can also increase the risk of getting a sunburn. Tell patients to use extra sunscreen and protective clothing if they use any products containing AHAs.

Also remind patients who take St. John’s wort that it is a very strong photosensitizer. Both oral and topical use can lead to sun poisoning. It contains the chemical hypericin, which seems to be responsible for these effects. Taking 1.8-4 grams St. John's wort extract or 5-10 mg hypericin daily seems to be the average dose range leading to increased sun sensitivity.

Bergamot oil is also one to watch out for. It’s often used in essential oil products, but when applied to the skin it can increase sun sensitivity. It contains a chemical called psoralen, which makes the skin more sensitive to ultraviolet (UV) light. Psoralens are found in some drugs used for psoriasis phototherapy treatment. Tell patients not to use bergamot oil on the skin.

Many other natural medicines also have photosensitizing effects. Refer to our photosensitizers chart to learn more.

The information in this brief report is intended for informational purposes only, and is meant to help users better understand health concerns. This information should not be interpreted as specific medical advice. Users should consult with a qualified healthcare provider for specific questions regarding therapies, diagnosis and/or health conditions, prior to making therapeutic decisions. Copyright © 2024 NatMed. Commercial distribution or reproduction prohibited. NatMed is the leading provider of high-quality, evidence-based, clinically-relevant information on natural medicine, dietary supplements, herbs, vitamins, minerals, functional foods, diets, complementary practices, CAM modalities, exercises and medical conditions. Monograph sections include interactions with herbs, drugs, foods and labs, contraindications, depletions, dosing, toxicology, adverse effects, pregnancy and lactation data, synonyms, safety and effectiveness.