What is the relationship between photosensitivity and doxycycline (tetracycline antibiotic)?

From the Guidelines

Doxycycline causes photosensitivity, so patients taking this antibiotic should take precautions to avoid sun exposure. While on doxycycline, patients should apply broad-spectrum sunscreen (SPF 30 or higher) to all exposed skin, wear protective clothing including hats and sunglasses, and limit time outdoors, especially between 10 AM and 4 PM when UV radiation is strongest. This photosensitivity can occur even on cloudy days and through window glass. The reaction typically manifests as an exaggerated sunburn with redness, pain, and sometimes blistering on sun-exposed areas, appearing within minutes to hours after exposure. This occurs because doxycycline absorbs UV radiation and generates reactive oxygen species in the skin, causing cellular damage. The photosensitivity risk persists throughout treatment and for several days after stopping the medication. If a severe reaction occurs, patients should seek medical attention and discuss with their healthcare provider whether to continue the medication or switch to an alternative antibiotic, as recommended by the CDC in their 2024 guidelines 1.

Some key points to consider when taking doxycycline include:

• Taking the medication with a full glass of water and on a full stomach to reduce the risk of esophagitis and gastrointestinal intolerance 1
• Avoiding lying down for 1 hour after taking doxycycline to prevent esophagitis 1
• Separating the doxycycline dose by at least 2 hours from dairy products, antacids, and supplements that contain calcium, iron, magnesium, or sodium bicarbonate to minimize potential drug interactions 1
• Being aware of the potential for photosensitivity and taking steps to mitigate this risk, such as avoiding prolonged sun exposure and using protective clothing and sunscreen 1

It's essential to follow the prescribed dosage and administration instructions for doxycycline to minimize the risk of adverse effects and ensure effective treatment. Patients should also be aware of the potential for drug interactions and take steps to minimize this risk, as recommended by the CDC in their 2024 guidelines 1.

From the FDA Drug Label

Photosensitivity manifested by an exaggerated sunburn reaction has been observed in some individuals taking tetracyclines. Patients apt to be exposed to direct sunlight or ultraviolet light should be advised that this reaction can occur with tetracycline drugs, and treatment should be discontinued at the first evidence of skin erythema. to avoid excessive sunlight or artificial ultraviolet light while receiving doxycycline and to discontinue therapy if phototoxicity (e.g., skin eruption, etc.) occurs.

Photosensitivity is a potential side effect of doxycycline. Patients taking doxycycline should be advised to:

• Avoid excessive sunlight or artificial ultraviolet light
• Discontinue therapy if phototoxicity occurs
• Use sunscreen or sunblock to reduce the risk of photosensitivity 2 2

From the Research

Photosensitivity and Doxycycline

• Photosensitivity is a known side effect of doxycycline, with clinical symptoms ranging from light sunburn-like sensation to large-area photodermatitis 3.
• The frequency of doxycycline-induced photosensitivity has been reported to vary from none to 15% in studies on the efficacy of doxycycline for treating erythema migrans 4.
• A study found that photosensitivity reactions occurred in 1.9% of patients treated with doxycycline 100 mg twice daily for 10-15 days, with women being more often affected than men 4.
• The triggering UV spectrum for doxycycline-induced phototoxicity seems to consist mainly of UVA1 (340-400 nm), highlighting the importance of using UV-protective products that cover this range 3.

Risk Factors and Prevention

• The risk of photosensitivity reactions is higher in patients treated with doxycycline for longer durations (14 or 15 days) compared to those treated for shorter durations (10 days) 4.
• Travelers to tropical countries taking doxycycline for malaria prophylaxis need thorough medical counseling to avoid possibly severe phototoxic reactions 3.
• Early recognition of doxycycline-induced phototoxicity is crucial, and identification of specific rashes, such as the "heart sign," can alert clinicians to the need for prompt intervention 5.

Long-term Risks

• Phototoxic reactions to doxycycline and other photosensitizing drugs may be associated with an increased risk of skin cancer, highlighting the importance of sun protection and careful consideration of the risks and benefits of these medications 6.