ive been on it (15 mg) for 2 years and personally i havent had any major side effects. it will make you a bit sleepy if your dose is between 5-15 mg. the lower your dose, the sleepier you will be. its also supposed to boost your appetite and it only really did that for me for about a few months. i does help a bit with anxiety as well.

I can't say that it really has been incredibly helpful for my anxiety. It has helped tremendously with my depression, however. I am currently taking Zyprexa for anxiety now. Mirtazapine made me gain weight. Only about 15 lbs and then I stabilized after that. It also made me sleepy at first (since it's also an antihistamine), but I built a tolerance to that effect overtime and now no longer get drowsy on antihistamines.