My son was prescribed doxycycline, 100mg, 1xday for acne. Within 3 days he began to have severe nausea and vomiting. The only change in his life has been this medication. We even saw a specialist and they never asked us about medication he was on. They just tested him for acid reflux-inconclusive results. He has also had headaches, blurry vision, itching, and chest pain.