Lexapro (escitalopram) causes side effects in a significant number of people who take it, with nausea, insomnia, fatigue, and sexual problems being the most frequently reported. Most of these are mild and tend to fade within the first few weeks, but some persist for as long as you take the medication. Here’s what to expect and what to watch for.
How Lexapro Works in Your Body
Lexapro is a selective serotonin reuptake inhibitor, or SSRI. It works by blocking the recycling of serotonin in the brain, which leaves more of it available between nerve cells. This boost in serotonin activity is what helps with depression and anxiety, but serotonin also plays roles in digestion, sleep, sexual function, and blood clotting. That’s why Lexapro’s side effects show up in so many different parts of the body.
One reason Lexapro tends to cause fewer side effects than some older antidepressants is that it’s highly selective. It has very little effect on other brain chemicals like dopamine, norepinephrine, or histamine. Older medications that block histamine receptors often cause heavy sedation and weight gain; Lexapro mostly avoids that.
The Most Common Side Effects
In clinical trials, the side effects that showed up most often (at roughly 5% or more, and at about twice the rate of a placebo) were nausea, insomnia, ejaculation problems in men, increased sweating, fatigue, and drowsiness. Dry mouth and decreased appetite are also common early on.
Nausea is typically the first thing people notice. It often starts within the first few days and is usually mild enough that it doesn’t require stopping the medication. Drowsiness and insomnia can seem contradictory, but some people experience one while others experience the other, depending on individual brain chemistry. Fatigue is common early on as well.
Most of these side effects peak in the first one to two weeks and then gradually fade as your body adjusts. It can take a few days to several weeks for this adjustment to happen. The therapeutic benefits of Lexapro, on the other hand, typically take longer to kick in, which means there’s often an awkward window where you feel the side effects before you feel the relief.
Sexual Side Effects
Sexual side effects are among the most common and most frustrating problems with Lexapro and other SSRIs. Estimates suggest that 30% to 50% of people taking SSRIs experience some form of sexual dysfunction, and some studies put the number even higher. The most frequently reported issues include reduced sex drive, difficulty reaching orgasm, and delayed ejaculation in men.
These side effects don’t always go away on their own. Unlike nausea or fatigue, which often resolve in the first few weeks, sexual side effects can persist for as long as you take the medication. They’re also one of the top reasons people stop taking antidepressants. If this is a concern, it’s worth discussing with your prescriber early, because adjusting the dose or switching medications can sometimes help.
Weight Changes Over Time
Lexapro causes relatively modest weight gain compared to some other antidepressants, but the effect does grow over time. A large study tracked by Harvard Health found that people taking escitalopram gained an average of 1.4 pounds at six months and 3.6 pounds at 24 months. That’s not dramatic, but it is a steady upward trend. Some people gain more, some gain nothing at all. Decreased appetite is actually common in the first few weeks, so early weight loss can sometimes mask the longer-term pattern.
Stopping Lexapro: Discontinuation Symptoms
Lexapro carries a moderate risk of discontinuation syndrome, meaning that stopping it abruptly can trigger a cluster of uncomfortable symptoms. These typically begin within two to four days of stopping and include flu-like feelings (fatigue, headache, achiness, sweating), nausea, dizziness, burning or electric shock-like sensations, vivid dreams or nightmares, and mood changes like irritability, anxiety, or agitation.
These symptoms are not dangerous in most cases, but they can be very unpleasant. The most effective way to resolve them is to resume the previous dose, which usually eliminates symptoms within 24 hours. The safe way to stop Lexapro is to taper gradually under a prescriber’s guidance, reducing the dose slowly over weeks or longer. Never stop cold turkey.
Serious Risks to Know About
Most Lexapro side effects are manageable, but a few rare ones require immediate attention.
Suicidal Thoughts in Young People
Lexapro carries an FDA black box warning, the most serious type, about increased risk of suicidal thinking and behavior in children, adolescents, and young adults (ages 18 to 24) during the early weeks of treatment. This risk was identified in short-term clinical trials. Adults over 24 did not show this increased risk, and adults 65 and older actually showed a reduced risk compared to placebo. Lexapro is not approved for anyone under 12. Close monitoring during the first weeks of treatment is essential for younger patients.
Serotonin Syndrome
Serotonin syndrome is a rare but potentially life-threatening reaction that happens when serotonin levels climb too high. It’s most likely to occur within 24 hours of a dose increase or when Lexapro is combined with another drug that raises serotonin, such as certain migraine medications (triptans), tramadol, lithium, St. John’s Wort, or other antidepressants. Symptoms include agitation, confusion, rapid heart rate, high blood pressure, muscle twitching, heavy sweating, and diarrhea. Severe cases can cause high fever, seizures, irregular heartbeat, and unconsciousness. This is a medical emergency.
Increased Bleeding Risk
Because serotonin plays a role in blood clotting through platelets, Lexapro can increase the risk of bleeding events. This risk is higher if you also take aspirin, ibuprofen, naproxen, or blood thinners. Upper gastrointestinal bleeding is the most commonly studied concern.
Low Sodium Levels
SSRIs can sometimes cause low sodium in the blood, a condition called hyponatremia. This is more common in older adults. Signs include headache, difficulty concentrating, memory problems, confusion, weakness, and unsteadiness that may lead to falls.
Other Rare Concerns
Lexapro can trigger a manic episode in people with undiagnosed or known bipolar disorder. It has also been associated with seizures in rare cases, particularly in people with a history of seizure disorders. In people with a specific eye anatomy (anatomically narrow angles), the pupil dilation caused by Lexapro can trigger a type of glaucoma attack.
What the First Weeks Typically Look Like
During the first week, expect mild side effects at lower starting doses. Nausea, diarrhea, and drowsiness are the most common early complaints. These often feel worse before they feel better, peaking somewhere around the first one to two weeks before tapering off. The therapeutic effects for depression or anxiety usually take four to six weeks to fully develop, so patience during this adjustment period is important. If side effects are severe or don’t improve after the first few weeks, that’s useful information to bring to your prescriber, who may adjust the dose or consider alternatives.