Lexapro (escitalopram) causes side effects in most people during the first few weeks, with nausea, drowsiness, and diarrhea being the most common. These early side effects are typically mild and tend to fade as your body adjusts, but some, particularly sexual side effects and weight changes, can persist for as long as you take the medication.
How Lexapro Causes Side Effects
Lexapro is a selective serotonin reuptake inhibitor, or SSRI. It works by blocking the brain’s ability to reabsorb serotonin, a chemical messenger involved in mood regulation. This leaves more serotonin available in the brain, which is how the drug treats depression and anxiety.
The catch is that serotonin doesn’t just operate in the brain. About 90% of the body’s serotonin is found in the gut, and serotonin also plays a role in sleep, appetite, blood clotting, and sexual function. When Lexapro raises serotonin levels across the board, those systems get affected too. That’s why the side effects span such a wide range, from stomach problems to insomnia to changes in sexual desire. Notably, Lexapro has very low affinity for the receptors responsible for sedation and cardiovascular problems seen with some older antidepressants, which is one reason it’s generally considered well-tolerated compared to earlier medications.
Common Side Effects in the First Few Weeks
Side effects tend to appear within the first few days of starting Lexapro or increasing the dose. The most frequently reported ones include:
- Nausea: the single most common complaint, often worse on an empty stomach
- Drowsiness or fatigue
- Diarrhea or constipation
- Dry mouth
- Insomnia
- Increased sweating
- Dizziness
- Headache
At lower starting doses, these effects are typically mild. It can take a few days to several weeks for your body to fully adjust, and most of these early side effects diminish or disappear entirely during that window. Taking Lexapro with food can help reduce nausea, and timing your dose in the morning or evening (depending on whether it makes you sleepy or wired) can ease sleep-related issues.
Sexual Side Effects
Sexual side effects are one of the most common reasons people consider switching antidepressants, and Lexapro is no exception. Research estimates that 60 to 80% of people taking antidepressants experience some form of sexual dysfunction, though Lexapro tends to fall on the lower end of that range compared to some other SSRIs. One study found that about 34% of women taking escitalopram reported sexual dysfunction, compared to 55% on fluoxetine (Prozac).
The most common sexual complaints include reduced sex drive, difficulty reaching orgasm, and for men, erectile dysfunction. Unlike nausea or dizziness, sexual side effects often don’t improve with time. They typically resolve after stopping the medication, though in rare cases some people report prolonged effects. If sexual side effects are significantly affecting your quality of life, dose adjustments or switching medications are options worth discussing with your prescriber.
Weight Changes Over Time
Weight gain with Lexapro is modest but real, and it tends to build gradually. Data from Harvard Health Publishing shows an average gain of about 1.4 pounds at six months and 3.6 pounds at two years. That’s less than some other antidepressants, but it’s not zero, and individual variation is wide. Some people gain more, some gain nothing, and a small number lose weight.
The mechanism isn’t fully understood, but changes in appetite, reduced physical activity from fatigue, and serotonin’s role in hunger signaling all likely play a part. If you notice steady weight gain after starting Lexapro, tracking your eating patterns and activity level can help you distinguish medication-related changes from other factors.
Increased Bleeding Risk
Serotonin plays an important role in blood clotting. Platelets (the blood cells responsible for clotting) rely on serotonin to function properly, and because Lexapro interferes with serotonin reuptake throughout the body, it can reduce the ability of platelets to form clots. This creates a modest increase in the risk of bleeding, particularly in the upper gastrointestinal tract. That risk climbs significantly if you’re also taking NSAIDs like ibuprofen or naproxen, or blood thinners like aspirin. If you regularly use pain relievers, it’s worth knowing that the combination carries more bleeding risk than either one alone.
Suicidal Thoughts in Young Adults
Lexapro carries an FDA boxed warning, the most serious type of safety alert, about an increased risk of suicidal thinking and behavior in children, adolescents, and young adults under 25. This risk was identified in short-term clinical trials comparing antidepressants to placebo. Adults over 24 did not show the same increased risk, and adults 65 and older actually showed a reduced risk of suicidality on antidepressants compared to placebo.
This doesn’t mean Lexapro causes suicidal behavior in most young people who take it. It does mean that mood and behavior should be monitored closely during the first several weeks, especially after dose changes. New or worsening anxiety, agitation, panic attacks, irritability, or impulsive behavior in the early weeks of treatment are worth reporting immediately.
Serotonin Syndrome
Serotonin syndrome is a rare but potentially dangerous reaction that happens when serotonin levels climb too high. It almost always involves taking two or more substances that raise serotonin at the same time. Combining Lexapro with migraine medications called triptans, older antidepressants called MAOIs, certain opioid painkillers, or even over-the-counter cough medicines containing dextromethorphan can trigger it. Street drugs like MDMA (ecstasy), cocaine, and amphetamines also raise serotonin and increase the risk.
Symptoms include agitation, confusion, rapid heart rate, heavy sweating, fever, muscle twitching, tremor, and loss of coordination. Three or more of these signs occurring together after starting or increasing a serotonin-affecting drug should be treated as a medical emergency. Serotonin syndrome develops quickly, often within hours, and resolves with appropriate treatment once the offending substances are removed.
What Happens When You Stop Lexapro
Stopping Lexapro abruptly can trigger discontinuation syndrome, a cluster of uncomfortable symptoms that appear within days of your last dose. The most distinctive symptom is “brain zaps,” described as brief electric shock sensations in the head, sometimes accompanied by dizziness, buzzing sounds, or the strange feeling of hearing your eyes move. Other discontinuation symptoms include irritability, nausea, insomnia, vivid dreams, and a general flu-like feeling. Brain zaps can happen repeatedly throughout the day and may even wake you from sleep.
These symptoms are not dangerous, but they can be disorienting and unpleasant. The way to avoid them is to taper your dose gradually over several weeks or months rather than stopping cold turkey. The right tapering schedule depends on how long you’ve been on the medication, your current dose, and how sensitive you are to dose changes. Discontinuation symptoms typically resolve within a few weeks of completing the taper, though some people experience them for longer.