Higher doses of doxycycline, such as of 100 milligrams (mg) a day or more, have an antibiotic effect and may contribute to ...

Doxycycline monohydrate 50mg, 100mg; tabs. Photosensitivity, GI upset, esophageal irritation/ulceration (drink fluids liberally with dose), rash, increased BUN, hypersensitivity reactions, blood ...

only a few cases have been reported with doses similar to that administered in the present case (100 mg/d). Doxycycline is one of the strongest photosensitizers, and phototoxicity is reportedly ...