Doxycycline Monohydrate Side Effects: I am being treated for lyme disease with 400mgs/day. I take 200m http://www.medications.com/effect/view/21933 I am being treated for lyme disease with 400mgs/day. I take 200mgs in the am and 200mgs in pm. The course of treatment is for 4wks. I am in my 2nd week. I feel just awful. My side effects are nausea, generalized weakness, fatigue, abdominal pain, heada Are you still taking medication? Do you know how long you had Lym Wed, 05 Mar 2008 15:30:37 -0500 http://www.medications.com/effect/view/21933?item=5319 Are you still taking medication? Do you know how long you had Lyme Disease before being treated? http://www.medications.com/effect/view/21933?item=5319