Starting an SSRI: the first six weeks.

Before day one: what your doctor covers.

SSRIs, the selective serotonin reuptake inhibitors like sertraline, escitalopram, and fluoxetine, are the most commonly prescribed first-line medications for depression and for several anxiety conditions. They're taken once daily, they aren't sedatives, and they don't work like a painkiller where you feel the dose. They work gradually, over weeks. The evidence behind them is real: in a network meta-analysis of 522 trials covering more than 116,000 patients, every antidepressant studied was more effective than placebo.^[1] Not dramatically for everyone, and not for everyone at all, but reliably better than nothing, which is why they've earned their place as a starting point.

A prescription should never be the first thing that happens. Before day one, a real evaluation covers why this medication, for this diagnosis, whether that's anxiety, depression, or both, since the two travel together more often than not. Your doctor should screen for things that change the plan entirely, like a history of manic episodes, and go through every medication and supplement you take, because some common ones interact with SSRIs. You should leave that first conversation knowing your starting dose, when to take it, what the first two weeks may feel like, and exactly when you'll talk again.

Weeks 1 and 2: the bumpy stretch.

Here's the part most marketing skips: for many people, the first week or two on an SSRI feels slightly worse before it feels better. The common early side effects are nausea or an unsettled stomach, headache, sleep changes in either direction, vivid dreams, appetite changes, and, especially if you're starting one for anxiety, a jittery, keyed-up feeling in the first days. None of this means the medication is failing. It means your body is adjusting, and most of these effects fade within one to three weeks.

This stretch is the drop-off danger zone. It's the worst possible trade to quit here: you've already paid most of the side-effect cost, and the benefit is closer than it feels. In fact, the old line that "nothing happens for a month" isn't quite true. A systematic review and meta-analysis found that measurable improvement begins within the first one to two weeks and builds gradually from there.^[2] It's just that early improvement is quiet. You won't feel a switch flip. You may simply notice, in retrospect, that a bad afternoon didn't swallow the whole day.

A few honest, practical notes for this stretch: take it with food if your stomach objects. If it makes you drowsy, ask about taking it at night; if it winds you up, ask about the morning. And go easy on alcohol, because it works against the medication and against your sleep.

Weeks 3 and 4: early signals.

Improvement usually arrives in an unglamorous order. Sleep steadies. Appetite normalizes. The fuse gets a little longer. You recover from bad moments faster, and the background rumination loses some volume. Mood itself, the part where you actually feel good, often lags behind these mechanical improvements, and the people around you may notice the change before you do. That's typical, not a sign you're doing it wrong.

These early signals matter more than they feel like they do. In a meta-analysis of over 6,500 patients, even modest improvement, about 20 percent, within the first two weeks strongly predicted eventually responding to the medication, while patients with no early improvement were much less likely to get there on that drug and dose.^[3] Translation: small progress now is genuinely good news. And if there's been no flicker of anything by weeks three to four, that isn't failure. It's useful information that moves the dose-or-switch conversation forward. Either way, this window is exactly when you and your doctor should be talking.

Weeks 5 and 6: fair-trial territory.

Psychiatric guidelines generally consider four to eight weeks at an adequate dose a fair trial, which is enough time to judge a medication honestly.^[4] By weeks five and six, you and your doctor can look at real evidence instead of hope: How's sleep? Energy? The worry volume? The dark stretches? What do the people close to you say?

Three outcomes, three next moves. Clearly better: continue, and know that benefits often keep consolidating past week six. Partly better: often the dose has room to move, since many people start below the dose that ultimately works. Not better at an adequate dose and duration: switching is normal medicine, not defeat. In the largest real-world antidepressant trial ever run, about one in three people reached remission on the first medication tried, and roughly two in three got there by working through further treatment steps with their clinician.^[5] The first prescription is a first attempt, not a verdict on you.

When to call sooner.

The six-week timeline is for the ordinary bumps. Some things should never wait for a scheduled follow-up:

• Your mood is clearly getting worse, not better: deeper, darker, or more hopeless than when you started.
• New or worsening thoughts of suicide or self-harm. Contact your clinician immediately, or call or text 988, the Suicide & Crisis Lifeline, any time, day or night. You don't need to be certain it's "bad enough." That's what it's for.
• Severe restlessness or agitation: feeling like you can't sit still, crawling out of your skin.
• Suddenly needing almost no sleep, with racing thoughts or unusually big plans. These can be signs of a manic reaction that changes the diagnosis and the treatment.
• Fever, sweating, tremor, confusion, or severe agitation, especially after adding another serotonergic medicine, can signal serotonin syndrome. That's emergency care: call 911.
• A rash, swelling, or trouble breathing. Treat that as an emergency.

The vigilance around mood isn't fine print. Antidepressants carry an FDA boxed warning for an increased risk of suicidal thoughts and behaviors in people 24 and younger, with the risk concentrated in the first months of treatment and after dose changes, which is why anyone starting an SSRI, at any age, should be monitored rather than handed a bottle and a goodbye.^[6]

Why you never stop abruptly.

At some point, whether because of side effects, because it isn't working, or because it worked and life moved on, most people eventually stop an SSRI. How you stop matters. Stopping abruptly can trigger discontinuation symptoms: dizziness, nausea, flu-like feelings, insomnia, irritability, anxiety, and odd electric-shock sensations people call "brain zaps." A systematic review found these symptoms typically appear within a few days of stopping and usually last a few weeks, and that they can occur even when the dose is lowered gradually, which is why tapering deserves a doctor's supervision rather than a guess.^[7]

Two takeaways. First, doses come down the way they went up: gradually, on a schedule your doctor builds with you. Second, and this one catches people at week six, don't stop just because you feel better. Feeling better is the medication working, not proof you no longer need it. How long to continue after recovery is a real conversation with real evidence behind it, and it belongs in a follow-up visit, not a Sunday-night decision over the sink.