Medications That Make You More Sensitive to the Sun

You apply your usual sunscreen, spend the same amount of time outdoors as always, and somehow end up with a burn far worse than anything you have experienced before. If this has happened to you shortly after starting a new medication, you are almost certainly dealing with drug-induced photosensitivity. More than 300 medications — from common antibiotics to over-the-counter painkillers — can dramatically increase how your skin reacts to UV radiation. Here is the science behind it and what you can do about it.

How Medications Make Your Skin More Sun-Sensitive

Drug-induced photosensitivity occurs when a medication — taken orally or applied topically — absorbs UV radiation and triggers a chemical reaction in or on the skin. The result is an amplified response to sunlight that goes well beyond what your skin would normally experience at the same UV dose.

The mechanism works like this: photosensitising drug molecules absorb UVA photons and enter an unstable excited state called the triplet state. From there, the molecules release energy in one of two ways — either by generating free radicals that directly damage cell membranes and DNA, or by producing reactive oxygen species (particularly singlet oxygen) that oxidise cellular components. Either pathway causes tissue damage that your body could normally handle at that UV dose, but which becomes overwhelming with the drug present.

Photosensitivity reactions account for roughly 8% of all adverse skin reactions to medications. Between 5% and 16% of referrals to photodermatology clinics are caused by drug-induced phototoxicity — making this far more common than most people realise.

Phototoxic vs. Photoallergic: Two Different Reactions

Not all drug-sun interactions work the same way. There are two distinct types, and telling them apart matters for how you manage them.

Phototoxic reactions are by far the more common type. They work like a chemical amplifier for sunburn — the drug absorbs UV energy and releases it directly into your skin cells. The more drug in your system and the more UV you receive, the worse the reaction. Anyone can experience a phototoxic reaction; it does not require a prior sensitisation.

Photoallergic reactions are rarer and more unpredictable. UV light alters the drug's chemical structure, causing it to bind to skin proteins and form a new compound that the immune system recognises as foreign. This triggers a delayed allergic response that can look like contact dermatitis and may even spread to skin that was not exposed to sunlight.

Which Medications Cause Sun Sensitivity?

The list is long — over 300 drugs have been implicated — but certain classes are responsible for the vast majority of cases.

Antibiotics

Tetracyclines are one of the most frequent causes of drug-induced photosensitivity. Doxycycline is the worst offender in this class — its chemical structure is particularly efficient at absorbing UVA radiation. Studies show that doxycycline can reduce the minimal erythemal dose (the amount of UV needed to produce redness) by 50% or more in some patients. Minocycline, by contrast, is the least photosensitising tetracycline.

Fluoroquinolones — including ciprofloxacin and levofloxacin — are another high-risk group, with phototoxic reactions documented in up to 10% of patients in some studies.

NSAIDs (Painkillers)

Over-the-counter anti-inflammatories including ibuprofen (Nurofen, Advil), naproxen (Aleve), and ketoprofen can all trigger photosensitivity. Naproxen is particularly notable because it can cause both phototoxic and photoallergic reactions.

Diuretics

Hydrochlorothiazide (HCTZ) — one of the most widely prescribed blood pressure medications in the world — is a well-documented photosensitiser. Research has linked long-term HCTZ use to a significantly increased risk of skin cancer: a 1.86-fold increase in squamous cell carcinoma risk and a 1.19-fold increase in basal cell carcinoma risk. The European Medicines Agency has added specific photosensitivity warnings to HCTZ product labels as a result.

Retinoids

Isotretinoin (Roaccutane/Accutane) thins the stratum corneum and weakens the skin's barrier function, making it substantially more vulnerable to UV. Dermatologists recommend SPF 50+ for isotretinoin patients, and photosensitivity can persist for up to six months after stopping treatment. Topical retinoids like tretinoin also increase sun sensitivity, which is why dermatologists advise applying them at night.

Other Common Culprits

Why UVA Is the Main Concern

Most drug-induced phototoxicity is driven by UVA radiation rather than UVB. This is important because UVA behaves differently from UVB in several ways that affect your risk:

• UVA penetrates deeper into the skin, reaching the dermis where it can damage collagen and blood vessels
• UVA passes through clouds and glass — you can trigger a phototoxic reaction sitting by a window on an overcast day
• UVA intensity is relatively constant throughout the day, unlike UVB which peaks at midday
• Many sunscreens offer weaker UVA protection than UVB — check for "broad-spectrum" on the label

This is why standard sunburn avoidance advice alone is not sufficient if you are on a photosensitising medication. You need to think about UVA exposure specifically.

How to Protect Yourself

If you are taking any medication on the lists above — or any drug whose leaflet mentions photosensitivity — these precautions are essential:

• Use broad-spectrum SPF 30+ sunscreen that explicitly covers UVA (look for the UVA circle logo in the EU, or "broad-spectrum" in the US). Reapply every two hours and after swimming or sweating.
• Wear protective clothing — long sleeves, a wide-brimmed hat, and UV-rated sunglasses. Tightly woven fabrics block more UV than loose weaves.
• Avoid peak UV hours — between 11:00 and 15:00 in summer. If your UV index is 3 or above, extra caution is warranted.
• Time your dose if possible — some prescribers recommend taking photosensitising medications in the evening rather than the morning, so that peak blood levels do not coincide with peak UV hours. Always check with your doctor before changing your dosing schedule.
• Do not assume shade is enough — reflected UV from sand, water, and concrete can still trigger reactions, especially when UVA is the culprit.
• Tell your prescriber if you spend significant time outdoors. There may be an alternative medication with a lower photosensitivity profile — for example, switching from doxycycline to minocycline, or from hydrochlorothiazide to an alternative antihypertensive.

Image: Doxycycline hyclate 100 mg capsules — Tony Webster via Wikimedia Commons, CC BY 4.0.

Sources

• Hofmann GA et al. Drug-induced photosensitivity: culprit drugs, potential mechanisms and clinical consequences. JDDG, 2021.
• Blakely KM et al. Drug-induced photosensitivity: Photoallergic and phototoxic reactions. Clinics in Dermatology, 2019.
• Kowalska J et al. Drug-Induced Photosensitivity — From Light and Chemistry to Biological Reactions and Clinical Symptoms. Pharmaceuticals, 2021.
• Monteiro AF et al. Drug-Induced Photosensitivity: Clinical Types of Phototoxicity and Photoallergy and Pathogenetic Mechanisms. Pharmaceuticals, 2022.
• Pedersen SA et al. Hydrochlorothiazide use and risk of nonmelanoma skin cancer. Journal of the American Academy of Dermatology, 2018.
• Yang H et al. Hydrochlorothiazide Use and Risk of Skin Cancer: A Population-Based Retrospective Cohort Study. Pharmacoepidemiology and Drug Safety, 2024.
• U.S. Food and Drug Administration. The Sun and Your Medicine. FDA.
• Skin Cancer Foundation. Photosensitivity Report — Medications.