I take Doxycycline off and on for mild acne. I noticed that I definitely had to eat a meal before I took a pill, and even then it always made me a bit nauseous. Last night I took one around midnight and went to bed. I woke up at quarter to 5 with chest pain. I got up and tried to eat something but that was painful too. I've been trying to drink water all day but it appears to have no effect. It's now 12 hours later and I still have chest pain, and I feel like vomiting. I will never take this again!