While in rare circumstances weight gain was a notable side effect, this happened only rarely and is not to be expected according to RxList, the Internet drug index. Many patients experienced weight loss when on Buspar instead of weight gain.
Buspar is an anti-anxiety agent. Common side effects include nausea, dizziness, insomnia, light-headedness and headaches. Most physicians normally prescribe Buspar in dosages from 10 to 30 mg per day in two to three divided doses to a maximum of 60 mg a day. Buspar is not typically recommended for pregnant women because it may place the fetus at risk.