Weight Gain from Taking Antibiotics?

I've been on minocycline for the past 3 years for hormonal acne. I was flipping through pictures and realized that it was about 3 years ago when I started putting on weight. Maybe its just a coincidence. I've been trying to lose weight by calorie restriction and exercise for the last couple months with no success. In fact, I've gained weight since I started.

Has anyone else been on a long term antibiotic and noticed any weight gain?