How long does Aminolevulinic acid stay in your system?
Last updated September 7, 2026.
**Aminolevulinic acid itself leaves your bloodstream within about a day, but the light-sensitizing compound it creates keeps you sensitive to bright light for roughly 40 to 48 hours after treatment.** The drug has a short half-life, so blood levels drop quickly, but your cells convert it into protoporphyrin IX, which is what makes skin and eyes react to light. That compound peaks within several hours and fades over about two days. The oral form used during brain tumor surgery and the topical forms used on actinic keratosis both carry a 40 to 48 hour light precaution. Reduced kidney or liver function, repeat doses, and a larger treated area can stretch that window. Plan to stay indoors away from windows, skip bright task lighting, and cover treated skin with clothing and a wide brimmed hat if you must go out.
What to do
- Count from your dose: Start the 40 to 48 hour clock at the time of application or the oral dose, not at the time of the light treatment.
- Block light, not just sun: Bright indoor lamps, operating room lights, and light through car and office windows can still trigger a reaction.
- Cover, do not just spray: Sunscreen does not block the visible light that activates this drug, so rely on clothing, hats, and staying indoors.
- Protect your eyes: After the oral form, wear sunglasses outdoors and dim screens and overhead lights for the first two days.
- Tell your team about your kidneys and liver: Reduced organ function can slow clearance and lengthen how long you stay sensitive.
- Call about lasting reactions: Contact your clinician if stinging, swelling, or blistering keeps getting worse past 48 hours or the treated area looks infected.
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