bacterial infection
"Several hours after my first dose I started having bad tendon pain in my shoulder and bicep area as well as a dull pain behind my right eye when looking any direction other than straight. After my second dose I began feeling mentally disconnected and later that night after my second dose my lips, tongue and throat began swelling. I was taken to the ER and was given an antihistamine shot alone with steroids and pepcid. The doctor told me not to take Doxycycline ever again. This drug may work for a lot of people but be careful and watch out for allergic reactions."