Doxycycline will be recommended by your health care provider if he thinks your infection has been caused by the presence of bacteria and you need this kind of treatment. If you are currently taking penicillin, anticoagulants, vitamins, antacids, phenobarbital, carbamazepine, or phenytoin, remember to report it to your doctor before the prescription is written. This fact can influence the dosage you will be prescribed as well as for how long you will have to take doxycycline - while some drug from the list can decrease the effectiveness of doxycycline, others may intensify its effects, including some side effects. It's very important that you do everything possible for your treatment to go as planed. This involves taking the right dosage regularly and telling your health care provider about any symptoms you develop that seem bothersome. There is a fine line between mild and serious side effects, and you should know the possible side effects that may occur when you just begin the treatment. It's important that you do not feel too worried if you have sores inside your mouth, diarrhea, trouble swallowing, vaginal discharge, vomiting, mild nausea, swollen tongue, stomach upset, swelling the genital area, or vaginal itching. These symptoms are just a sign of your body trying to deal with the dosage and the fact you are actually taking some medicine. These side effects are considered to be mild and you should report them to your doctor only if they get worse, do not go away after a couple of days and start to interfere with your everyday activities.