Lexapro will likely make you feel different at various stages, and the first few weeks won’t reflect what the medication ultimately does for you. Early on, you may notice physical side effects before any mood improvement. The full therapeutic effect typically takes four to six weeks, and what you experience along the way depends on your dose, your body, and what you’re treating.
How Lexapro Works in Your Brain
Lexapro works by slowing the reabsorption of serotonin, a chemical messenger involved in mood regulation, sleep, and appetite. Normally, after serotonin delivers its signal between nerve cells, it gets pulled back in and recycled. Lexapro blocks that recycling process, leaving more serotonin available to keep working. This shift in brain chemistry happens quickly, but the downstream effects on your mood take weeks to build.
What the First Two Weeks Feel Like
The earliest days on Lexapro are often the roughest. Your brain is adjusting to a new chemical environment, and it tends to protest before it settles in. Common sensations during the first week or two include nausea, headaches, jitteriness, and changes in appetite. Some people feel more anxious than usual, which can be alarming when you started the medication to reduce anxiety in the first place. This is a well-known pattern with SSRIs and it’s temporary.
Drowsiness is one of the more common effects. About 13% of people taking Lexapro experience noticeable sleepiness, roughly double the rate seen with a placebo. At higher doses, the effect is more pronounced. Some people find this helpful if they’ve been struggling with insomnia, while others find daytime fatigue frustrating. A smaller number of people experience the opposite: difficulty falling or staying asleep.
Not everything in this window is unpleasant. Some people notice early improvements in sleep quality, energy levels, or appetite within the first one to two weeks. These are often the first signs that the medication is starting to work, even before your mood shifts.
When Mood Improvement Kicks In
The relief most people are hoping for, a lighter mood, less dread, renewed interest in things you used to enjoy, generally takes longer. Expect four to six weeks for meaningful improvement, and in some cases up to eight weeks for the full effect. This is one of the hardest parts of starting Lexapro: you’re managing side effects while waiting for the payoff.
When it does start working, the change is often subtle. You might realize one afternoon that you didn’t spend the morning ruminating, or that a social event didn’t feel like a chore. People rarely describe a dramatic “switch” moment. It’s more like gradually noticing that the volume on your anxiety or sadness has been turned down. Tasks that felt impossible start feeling merely difficult, then manageable.
Emotional Blunting
One of the more surprising effects of Lexapro is something called emotional blunting. Between 40% and 60% of people on SSRIs report this: a flattened emotional range where both the lows and the highs feel muted. You might find that sad movies don’t make you cry anymore, but also that good news doesn’t excite you the way it used to. Things that once brought genuine pleasure, a favorite song, a beautiful day, can feel oddly neutral.
Researchers at the University of Cambridge have noted that this blunting may actually be part of how SSRIs work. The medication dampens the emotional pain of depression, but it can also dampen enjoyment. For some people, this tradeoff feels worthwhile. The crushing lows are gone, and a steady “okay” is a major upgrade. For others, the flatness becomes its own problem. If you feel like you’re watching your life through glass rather than living it, that’s worth bringing up with whoever prescribed your medication, because adjusting the dose or switching drugs can help.
Effects on Weight
Weight changes on Lexapro are real but modest for most people. Research published through Harvard Health found that Lexapro led to an average gain of about 1.4 pounds at six months and 3.6 pounds at two years. That’s on the lower end compared to many other antidepressants. Some people gain more, some lose weight initially (especially if nausea suppresses appetite early on), and plenty notice no meaningful change at all. If your depression or anxiety was already affecting your eating habits, your weight may shift simply because your appetite normalizes.
Sexual Side Effects
Reduced sex drive and difficulty reaching orgasm are among the most common complaints with Lexapro and SSRIs in general. These effects can show up early and persist for as long as you’re on the medication. Some people experience a noticeable drop in desire, while others find that arousal and sensation are dulled even when desire is there. This is one of the top reasons people consider switching medications, and it’s a legitimate concern to raise with your prescriber rather than something to just push through.
What Happens If You Stop
Lexapro should never be stopped abruptly. Discontinuation syndrome can produce a distinctive set of symptoms, the most infamous being “brain zaps.” These feel like brief electrical jolts inside your head, lasting about a second each. People describe them as a shock sensation accompanied by a strange “whoosh” sound when they move their eyes. Some also experience jerky eye movements, dizziness, vertigo, and a feeling like the brain briefly pauses and reboots.
Beyond brain zaps, stopping too quickly can cause flu-like symptoms, nausea, insomnia, irritability, and a rebound of the anxiety or depression the medication was managing. These symptoms don’t mean you’re addicted. They’re your brain readjusting to operating without the drug’s influence on serotonin. A gradual taper, reducing the dose slowly over weeks or months, minimizes these effects significantly.
A Rare but Serious Risk
Serotonin syndrome is uncommon but worth knowing about, especially if you take other medications that affect serotonin (certain migraine drugs, pain medications, supplements like St. John’s wort, or other antidepressants). It happens when serotonin levels climb too high. Early warning signs include agitation, restlessness, rapid heartbeat, heavy sweating, diarrhea, and muscle twitching. Severe cases can involve high fever, seizures, and irregular heartbeat. This is a medical emergency. If you develop these symptoms after starting Lexapro or increasing your dose, get to an emergency room.