Your skin may react differently to the sun with certain medications or factors. This is called photosensitization: a phenomenon that makes the skin more fragile to UV rays. But don't worry... we'll explain everything in this article, including how to protect yourself on a daily basis.
What is the definition of photosensitization?
Photosensitization is an exponential reaction of the skin when exposed to UV rays in the presence of photosensitizing substances. These substances, often of medicinal or cosmetic origin, increase skin sensitivity and can trigger localized or widespread cutaneous reactions.
What are photosensitizing drugs?
Several drug families are known for their photosensitizing potential. Here are a few examples:
- Antibiotics;
- Non-steroidal anti-inflammatory drugs (NSAIDs)
- Diuretics;
- Antidepressants and psychotropic drugs;
- Oral antidiabetic agents.
Caution: These drugs can increase UV absorption and trigger adverse reactions. It's important to understand the side effects of certain medications in order to avoid skin reactions. Ask your pharmacist for more information about your medications.
What are the differences between phototoxicity and photoallergy?
Phototoxicity manifests itself as a "sunburn" effect that is brutal and immediate, sometimes causing a lesion with oedema and blisters.
Photoallergy reflects a delayed immune reaction, sometimes extended to unexposed areas. It requires a very low dose of medication to appear, and is most common in patients using topically applied treatments (creams, ointments).
What role does UV play in photosensitization?
Ultraviolet (UV) rays fall into three categories (UVA, UVB, UVC), but it is primarily UVA that causes drug-induced photosensitization reactions.
- UVA rays penetrate deep into the dermis and are responsible for phototoxicities and photoallergies.
- UVB rays are more energetic and mostly cause the "classic sunburn".
Did you know? Tanning salons, which use 95% UVA rays, are a major source of risk.
How does photosensitization manifest itself?
Symptoms vary based on the intensity of the reaction and the area exposed:
- Redness and skin overheating;
- Burns similar to sunburn;
- Vesicular rash or blisters;
- Post-inflammatory hyperpigmentation;
- Itching.
Uncovered areas are often the most affected, since they are the most exposed to the sun's rays: face, hands, forearms). Don't take any unnecessary risks; apply a generous amount of sunscreen to these areas of your body.
Antibiotics and the sun: do they mix?
Find all the answers in our article dedicated to this closely related topic: "Antibiotics and the sun: beware of the risks".
How long does photosensitization last?
Photosensitization may persist for several days to a few weeks after the photosensitizing drug has been discontinued. Symptoms generally diminish gradually 7 to 14 days after the last exposure to UV rays and the elimination of the substance.
How can I protect myself against photosensitization?
- Check the list of side effects of your medications, and ask your pharmacist for advice.
- Avoid direct exposure between 11 a.m. and 4 p.m., when UV rays are most intense.
- Apply a high-protection sunscreen (SPF 30 or higher) every two hours, and after every swim or heavy perspiration.
- Wear covering clothing, wide-brimmed hat and sunglasses, UV filter, etc.
If, when exposed to the sun, your skin reacts when you've taken certain medications (mentioned earlier in the article), take a moment to learn more about the harmful effects of the sun on the skin and health. It's also important to protect your skin well and to know the definition of sun cream protection indices. For that check out our article: "What exactly is SPF?"
What is a photosensitive person?
A photosensitive person shows increased skin reactivity to sunlight, even in the absence of medication. This may be due to:
- Fair or depigmented skin (phototype types I and II);
- Dermatological history (eczema, lupus, porphyria);
- Special genetics (albinism).
If you fall into one of these categories, it's important to be extra vigilant in the sun. The risks are too high to ignore this factor. Talk to a healthcare professional if you have any doubts or begin to notice unwanted effects.
List of photosensitizing food supplements and natural cosmetics
In addition to medications, certain skin care products and natural herbal ingredients can increase the skin's sensitivity to UV rays.
- St. John's wort: used in phytotherapy for its antidepressant virtues, which can trigger severe reactions to the sun when taken orally or applied topically.
- Citrus essential oils (bergamot, sweet orange): concentrated in photosensitizing compounds, they should be avoided before direct sun exposure.
- Certain fragrances and botanical extracts: even in very small quantities, they can sensitize the skin in association with UV rays.
Is vitamin C photosensitizing?
No, vitamin C is not at all photosensitizing. On the contrary, it is an antioxidant that boosts skin protection against UV rays. Ask your pharmacist for more information.
Tip: If you regularly use natural skincare products or cosmetics rich in plant extracts, ask your pharmacist to help you adjust your beauty routine safely.
List of photosensitizing drugs to avoid
- Tetracyclines: Doxycycline, minocycline;
- Fluoroquinolones: Ciprofloxacin, levofloxacin, moxifloxacin;
- Thiazide diuretics: Hydrochlorothiazide;
- Tricyclic antidepressants: Amitriptyline, imipramine;
- Antipsychotics: Chlorpromazine;
- Antidiabetics: Glyburide;
- Non-steroidal anti-inflammatory drugs: Ibuprofen, naproxen, celecoxib;
- Antifungals: Griseofulvin.
To avoid any damage to your skin, it's essential to adjust your medication accordingly. Consult your pharmacist to find the best alternatives.
What are the long-term consequences of photosensitization?
In the long term, symptoms caused by photosensitization can leave lasting marks on your skin.
- Increased pigmentation spots (melasma, lentigos), which may become permanent, even after discontinuation of the treatment causing the issue.
- Degradation of your collagen, leading to premature ageing with wrinkles and sagging skin.
- Damage to your DNA due to UV rays, which increase the risk of skin cancers (carcinomas, melanomas), all the more so in fair-skinned people or those with a history of phototoxic reactions.
To enjoy the sun all year round, and especially in summer, adopt appropriate photoprotection (SPF 30+ cream, covering clothing, UV400 sunglasses), keep an eye on the list of photosensitizing substances, and don't hesitate to consult your pharmacist or dermatologist at the first signs of photosensitization. In this way, you can enjoy the sun in complete safety, while preserving the health and radiance of your skin.
