SSRIs: What They Are, How They Work, and What You Need to Know

When doctors prescribe an antidepressant, SSRIs, selective serotonin reuptake inhibitors that increase serotonin levels in the brain to improve mood and reduce anxiety. Also known as serotonin reuptake inhibitors, they’re among the most commonly used psychiatric medications in North America. Unlike older antidepressants, SSRIs don’t cause severe dry mouth, dizziness, or heart rhythm issues for most people—which is why they’re often the first choice for depression, OCD, panic disorder, and even chronic anxiety.

But SSRIs aren’t magic pills. They take weeks to work, and the first few days can feel worse before they get better. Some people get nausea, headaches, or trouble sleeping. Others notice excessive sweating, a common side effect caused by serotonin’s effect on the body’s temperature control system, or feel emotionally numb. These aren’t rare—they’re expected in about 1 in 3 users. That’s why knowing which SSRIs, including fluoxetine, sertraline, escitalopram, and paroxetine cause which side effects matters. For example, paroxetine is more likely to cause weight gain and drowsiness, while fluoxetine tends to be activating and stays in your system longer.

SSRIs don’t play well with everything. Mixing them with NSAIDs like ibuprofen can raise your risk of bleeding, especially if you’re also on blood thinners. Taking them with certain pain meds, migraine drugs, or even St. John’s wort can trigger serotonin syndrome—a rare but dangerous spike in serotonin that causes confusion, rapid heartbeat, and muscle rigidity. Even something as simple as fiber supplements, used for constipation, can delay how fast SSRIs get absorbed if taken at the same time. That’s why medication reviews are so important. You need to know what’s in your cabinet, what your doctor knows, and what your pharmacist can flag.

Many people stop SSRIs too soon because they don’t feel better fast enough—or because side effects feel unbearable. But quitting cold turkey can cause dizziness, electric-shock feelings, and rebound anxiety. Tapering off slowly under supervision is the only safe way. And if one SSRI doesn’t work, it doesn’t mean they all won’t. Different SSRIs affect your body in slightly different ways, so switching isn’t failure—it’s fine-tuning.

Below, you’ll find real-world guides on how SSRIs interact with other drugs, how to handle side effects like sweating or drowsiness, what to watch for when combining them with other meds, and how to talk to your doctor about making changes without risking your mental health. These aren’t theory pieces—they’re practical, tested advice from people who’ve been there.