Zoloft (sertraline) is available only by prescription and is most commonly used to correct the imbalance of chemicals in the brain helping to treat depression and a number of other conditions. Zoloft is commonly well tolerated, although some mild side effects are reported by patients as they adjust to the new drug. These mild side effects reported include diarrhea, insomnia, dry mouth, drowsiness, nausea, weight loss, impotence and decreased sex drive. Do not stop taking Zoloft without previously discussing it with your health care provider. You also must not change your dose without your doctor's consent as it is not known what effects you are likely to experience.