Does cephalexin (a cephalosporin antibiotic) cause photosensitivity?

Cephalexin Does Not Cause Photosensitivity

Cephalexin is not associated with photosensitivity reactions and is recommended as a preferred alternative for patients concerned about sun sensitivity, unlike tetracyclines and fluoroquinolones which are well-documented photosensitizers. 1, 2

Evidence-Based Recommendation

The clinical guidelines are clear and consistent on this issue:

• Cephalexin lacks photosensitivity risk and should be considered as an alternative to tetracyclines for patients with outdoor activities or sun exposure concerns 1
• The Centers for Disease Control and Prevention specifically recommends cephalexin over tetracyclines or fluoroquinolones for patients with a history of photosensitivity reactions when clinically appropriate 1
• The Journal of the American Academy of Dermatology recommends cephalexin as an alternative to tetracyclines for treating acne in patients with outdoor activities specifically because it does not cause photosensitivity 1

Antibiotics That DO Cause Photosensitivity

For context, the following antibiotics are well-documented photosensitizers and should be avoided in sun-exposed patients:

• Tetracyclines (especially doxycycline and demeclocycline) cause exaggerated sunburn reactions 1, 3, 4
• Fluoroquinolones have significant phototoxic potential 3, 4
• Sulfonamides are known photosensitizers 3, 4

Clinical Management When Prescribing Photosensitizing Antibiotics

When you must prescribe known photosensitizers like doxycycline, the American Academy of Dermatology and CDC recommend:

• Avoid prolonged direct sun exposure 1
• Use sunscreens that absorb long-wave ultraviolet (UVA) radiation 1
• Take the medication in the evening to minimize daytime sun exposure risk 1

Important Caveat

While one in vitro laboratory study showed cephalexin could generate singlet oxygen under UV-B radiation exposure (290-320 nm) 5, this finding has no clinical relevance. This was a test-tube experiment examining direct UV exposure to the drug molecule itself, not a clinical photosensitivity reaction in patients. The clinical guidelines based on real-world patient data consistently confirm cephalexin does not cause photosensitivity in practice 1, 2.