Based on NIH | Can sertraline cause increased anxiety or restlessness when starting treatment, and how long does this side effect typically last?

Short answer

Yes, sertraline can cause increased anxiety, agitation, restlessness (including akathisia, a form of inner restlessness), and insomnia when you first start or when the dose is changed. These symptoms tend to appear early, often within the first days to weeks, and in many people they lessen over 1–2 weeks as the body adjusts; if they persist or are severe, your prescriber may reduce the dose, add a short‑term calming medicine, or switch therapies. ^{[1] [2]}

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Why this happens

• Early serotonergic activation: When sertraline (a selective serotonin reuptake inhibitor, SSRI) is started, serotonin signaling increases quickly, which can transiently heighten anxiety and agitation before the longer‑term calming effects emerge. This “activation” phase is well recognized across antidepressants. ^[1]
• Akathisia (psychomotor restlessness): Some people experience a compelling urge to move, inner tension, and inability to sit still; this can start soon after initiation or a dose increase. It is specifically listed among early treatment behavioral changes with antidepressants. ^[1]

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How common and how severe?

• Early anxiety/agitation/restlessness: These behavioral changes have been reported in patients early in treatment and around dose adjustments; families and caregivers are advised to monitor day‑to‑day for these symptoms. They can vary from mild and self‑limited to bothersome, and clinicians sometimes add short‑term supportive medicines if needed. ^[1]
• Serious warning signs: New or worsening anxiety, severe restlessness, panic attacks, trouble sleeping, irritability, or frenzied excitement deserve prompt attention especially if accompanied by suicidal thoughts or unusual changes in behavior. Seek medical advice immediately if these occur. ^[2]

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Typical timeline

• Onset: Often within the first few days to the first couple of weeks after starting sertraline or after a dose change. ^[1]
• Duration: In many users, activation symptoms ease over 1–2 weeks as the nervous system adapts; persistence beyond this timeline, worsening symptoms, or marked distress warrants reassessment. ^[1]
• Course with treatment: If symptoms are significant, clinicians may respond by adjusting the dose, using a temporary sedative/hypnotic or beta‑blocker for restlessness, or considering an alternative medication if intolerance is clear. ^{[1] [3]}

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What you can do

• Start low, go slow: Using a lower starting dose and gradual titration can reduce early activation. Discuss dosing strategy with your prescriber before changes. ^[1]
• Monitor daily: Track anxiety, sleep, and restlessness during the first weeks and after dose changes; involve a trusted person to help notice changes. ^[1]
• Lifestyle supports: Sleep hygiene, caffeine moderation, regular light exercise, and relaxation techniques may ease transient activation. (These are supportive and do not replace medical guidance.)
• When to call your clinician: If anxiety/restlessness is severe, lasts beyond 1–2 weeks, interferes with daily functioning, or is accompanied by unusual behavior or suicidal thoughts, contact your clinician promptly. Emergency help is warranted for suicidal intent or inability to ensure safety. ^{[2] [1]}

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Important interactions and safety notes

• MAO inhibitors: Never combine sertraline with MAO inhibitors; and maintain a 14‑day washout both ways to prevent dangerous reactions such as agitation, restlessness, fever, high blood pressure, and confusion. ^{[4] [5]}
• Ongoing vigilance: Behavioral changes (anxiety, agitation, akathisia, insomnia, hypomania/mania) can occur early and around dose adjustments; consistent monitoring is advised throughout the initial months of therapy. ^[1]

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Bottom line

• It is possible and relatively well‑recognized for sertraline to briefly increase anxiety, agitation, and restlessness at the start or after dose changes. ^[1]
• For many people, these effects improve over about 1–2 weeks as the body adapts; if they do not, or if they are intense, your clinician may adjust the plan (dose changes, short‑term adjuncts, or medication switch). ^[1]
• Urgent symptoms such as severe restlessness, frenzied excitement, or suicidal thoughts need immediate medical attention. ^[2]