Lexapro (Escitalopram) Side Effects in the First Week: What Is Normal and What to Watch For

Why does Lexapro cause early side effects?

Lexapro (escitalopram) is an SSRI — a selective serotonin reuptake inhibitor — commonly prescribed for depression and generalized anxiety disorder. It works by increasing the availability of serotonin in the brain. When you first start, your brain is adjusting to a new level of serotonin signaling. This adjustment period is what drives most early side effects. It is not a sign the medication is wrong for you; it is the system calibrating.

SSRIs as a class are well-established treatments for depression and anxiety 1Ref 1DeGeorge KC, Grover M, Streeter GS (2022).Generalized Anxiety Disorder and Panic Disorder in Adults.SSRIs are well-established first-line treatments for generalized anxiety disorder and depression., and escitalopram in particular is widely prescribed because of its tolerability profile.

What early side effects are normal and usually temporary?

These are the side effects most commonly reported in the first one to two weeks:

Nausea — One of the most common early effects. Taking the medication with food usually helps. It typically improves within one to two weeks.

Fatigue or drowsiness — Some people feel more tired than usual early on. Ask your prescriber whether switching to a nighttime dose might help if this is significant.

Headache — Often mild and short-lived. Standard over-the-counter pain relief can help — check with your pharmacist about interactions.

Increased anxiety or restlessness — This one can feel alarming. SSRIs can temporarily increase anxiety or produce a jittery, restless feeling (sometimes called activation) before calming effects develop. This is especially common in the first couple of weeks and is more pronounced in people prescribed Lexapro primarily for anxiety. Prescribers sometimes start at a lower dose in this group to reduce this effect.

Insomnia or sleep changes — Difficulty falling asleep or more vivid dreams are sometimes reported early on.

Sweating — Mild increased sweating, especially at night, is sometimes reported.

Sexual side effects — These can appear early but are more often reported as a persistent effect once the therapeutic dose is established.

When should I call my prescriber instead of waiting it out?

Most early side effects are manageable and temporary. Contact your prescriber if:

• Nausea or vomiting is severe and interfering with eating or hydration.
• Anxiety or restlessness is markedly worse than before you started and is not improving after the first couple of weeks.
• You have any side effects that are significantly disrupting your daily life.
• You are thinking about stopping the medication — your prescriber can help you weigh the decision safely and consider alternatives.

Do not stop Lexapro abruptly. Stopping suddenly can cause antidepressant discontinuation syndrome — dizziness, irritability, flu-like feeling, and 'brain zaps' — even after a relatively short time on the medication 2Ref 2Warner CH, Bobo W, Warner C, Reid S, Rachal J (2006).Antidepressant Discontinuation Syndrome.Abrupt discontinuation of SSRIs including escitalopram can cause discontinuation syndrome with dizziness, irritability, and 'brain zaps'..

What should I expect as weeks go on?

Most early side effects improve by weeks two to three. Therapeutic benefits — improved mood, reduced anxiety, more emotional resilience — typically begin to emerge between two and four weeks. The full effect often takes six to eight weeks or longer. This time lag is normal and reflects the gradual way SSRIs change brain signaling.

If you have seen no benefit at all by six to eight weeks, that is worth discussing with your prescriber — not a reason to give up on treatment in general, but a prompt to reassess dose or consider alternatives.

Who needs extra monitoring in the early weeks?

Adolescents and young adults (under 25): Clinical guidelines identify a small increased risk of suicidal thinking in this age group during the early weeks of antidepressant treatment. More frequent check-ins are standard of care in this population 3Ref 3National Institute of Mental Health (2023).Depression.Adolescents and young adults under 25 require closer monitoring on antidepressants due to small increased risk of suicidal thinking early in treatment..

People with a history of bipolar disorder: SSRIs prescribed without a mood stabilizer in someone with undiagnosed bipolar disorder can trigger a manic episode 4Ref 4National Institute of Mental Health (2023).Bipolar Disorder.SSRIs prescribed without a mood stabilizer in someone with undiagnosed bipolar disorder can trigger manic episodes; personal or family history of bipolar is important clinical information.. A personal or family history of bipolar disorder is important information for your prescriber.

People taking other serotonergic medications: Combining Lexapro with certain migraine medications, some pain relievers, St. John's Wort, or other antidepressants raises the risk of serotonin syndrome — a rare but serious drug interaction.