Antidepressant Discontinuation Syndrome (ADS) can occur when you stop taking an antidepressant you’ve been on for at least six weeks. It’s more likely to happen if you stop suddenly rather than gradually tapering off under your doctor’s guidance. ADS can cause symptoms like insomnia, nausea, and flu-like feelings, which usually last less than two months. Some people call it “antidepressant withdrawal.” While ADS isn’t typically dangerous, it can be very uncomfortable. Plus, stopping an antidepressant could bring back the condition it was treating, like depression or anxiety.