Sertraline: What to Expect in the First Weeks

Starting sertraline can feel like a big step. You may be hoping it will help with depression, anxiety, panic attacks, OCD, PTSD or social anxiety, but you may also feel nervous about side effects, how long it will take to work, and whether you will still feel like yourself.

Sertraline is a commonly prescribed antidepressant. It belongs to a group of medicines called selective serotonin reuptake inhibitors, or SSRIs. These medicines affect serotonin, a chemical involved in mood, anxiety and emotional regulation.

The first few weeks can be a period of adjustment. Some people feel side effects before they feel benefits. Some feel slightly worse before they begin to feel better. Others notice small improvements quite early, such as sleeping a little better, feeling less tearful, or finding everyday tasks slightly easier.

This guide explains what to expect when starting sertraline, how long it may take to work, common early side effects, what to do if you feel worse, and when to seek medical help.

What sertraline is used for

Sertraline is used to treat several mental health conditions. It may be prescribed for depression, panic disorder, obsessive compulsive disorder, post-traumatic stress disorder and social anxiety disorder.

Some people are prescribed it for other reasons depending on their symptoms and clinical history.

The NHS describes sertraline as an SSRI antidepressant that may be used for depression, OCD, panic disorder, PTSD and social anxiety disorder. You can read the NHS guide to sertraline for official information.

Sertraline does not change your personality or make problems disappear overnight. The aim is usually to reduce the intensity of symptoms enough that you can function better, sleep better, engage with therapy or self-help, and start rebuilding daily routines.

If you are still exploring different support options, our guides to mental health support options in the UK, how to access mental health services and online therapy and counselling may be useful.

How long sertraline takes to work

Sertraline does not usually work immediately. NHS guidance says antidepressants usually take 1 to 2 weeks to start having an effect and can take up to 8 weeks to work fully.

Some people notice early changes sooner, while others need more time.

In the first week or two, you may notice changes in sleep, appetite, energy or anxiety before your mood clearly improves. For anxiety disorders, panic, OCD or PTSD, it can sometimes take longer for the full benefit to become clear.

This waiting period can be frustrating. It is common to wonder whether the medicine is doing anything.

Unless you have severe side effects or have been told otherwise, it is usually important to keep taking sertraline as prescribed and review progress with your prescriber.

The first few weeks on sertraline

The first few weeks are often about your body adjusting to the medicine. This is also the period when people may feel most unsure about whether to continue, especially if side effects appear before benefits.

The first few days

The first few days are often about your body getting used to the medicine. Some people feel almost no side effects. Others notice nausea, headache, loose stools, reduced appetite, dry mouth, tiredness, restlessness or sleep changes.

These early side effects are often mild and may improve after the first week or two. Taking sertraline with food can help some people who feel nauseous, although you should follow the instructions given by your prescriber or pharmacist.

You may also feel more aware of your symptoms because starting medication can bring hope, worry and close self-monitoring. Try not to judge whether sertraline is “working” after only a few days.

Week 1 to 2: side effects can appear before benefits

During the first couple of weeks, side effects may still be present. Some people feel slightly more anxious, restless or unsettled at first. This can be especially difficult if you started sertraline for anxiety or panic symptoms.

Common early side effects can include:

• feeling sick or having an upset stomach
• diarrhoea or changes in bowel habits
• headache
• dry mouth
• sleepiness or tiredness
• difficulty sleeping
• increased sweating
• shakiness or feeling jittery
• reduced appetite
• changes in sex drive or sexual function

The Royal College of Psychiatrists notes that SSRI and SNRI side effects are often mild and wear off over a couple of weeks, although you should speak to your doctor if symptoms are concerning or unbearable. Their guide to antidepressants gives more detail.

If side effects are difficult, do not stop suddenly without advice. Speak to your GP, prescriber or pharmacist. Sometimes side effects can be managed by adjusting the timing of the dose, reviewing other medicines, or allowing more time. In other cases, the dose or medicine may need review.

Week 3 to 4: small improvements may become clearer

By weeks three and four, some people begin to notice more meaningful changes. These may be subtle at first.

You may find you cry less often, recover from anxious thoughts more quickly, sleep more steadily, feel less irritable, or find it slightly easier to get through the day.

Improvement is not always steady. You may have better days and worse days. This does not mean sertraline has stopped working. Mental health recovery often happens in uneven steps rather than a straight line.

If you feel no improvement at all after several weeks, speak to your prescriber. They may suggest continuing a little longer, changing the dose, checking side effects, reviewing the diagnosis, adding talking therapy, or considering another treatment.

Week 6 to 8: reviewing whether it is helping

By six to eight weeks, it is usually easier to judge whether sertraline is helping. Some people feel a clear benefit. Others feel partial improvement but still have symptoms. Some do not feel better or cannot tolerate side effects.

A review with your GP or prescriber is important. Be honest about what has changed, what has not changed, and any side effects you are experiencing.

It can help to bring notes about sleep, mood, anxiety, panic attacks, appetite, energy, side effects and any thoughts of self-harm.

Do not increase or reduce the dose yourself. Sertraline dosing should be guided by a clinician, especially if you are taking other medicines or have other health conditions.

Can sertraline make you feel worse at first?

Some people do feel worse at first. This may include increased anxiety, restlessness, sleep disruption, nausea, emotional sensitivity or feeling unsettled.

For many people, this improves as the body adjusts.

However, worsening mood should always be taken seriously. Contact your GP or prescriber promptly if you feel more depressed, unusually agitated, impulsive, emotionally unstable, or if you develop thoughts of self-harm.

Younger adults, especially people under 25, may need closer monitoring when starting antidepressants because suicidal thoughts can sometimes increase early in treatment.

If you are supporting a young person starting sertraline, check in regularly and encourage them to tell someone if they feel worse.

Sertraline and suicidal thoughts

Starting antidepressants can be a vulnerable time. Some people may experience increased suicidal thoughts, especially early in treatment or after a dose change.

This does not mean sertraline is “bad” or that you should panic, but it does mean support and monitoring matter.

Contact your GP, crisis team or NHS 111 urgently if you:

• feel more hopeless
• start thinking about self-harm
• feel unsafe alone
• feel unusually agitated or impulsive
• notice sudden worsening after starting or changing dose

If there is immediate danger, call 999 or go to A&E. You can also call Samaritans free on 116 123 at any time.

Feeling unusually energised or restless

Feeling a little restless or jittery early on can happen. But if you feel unusually energised, unable to sleep, impulsive, euphoric, agitated, reckless or unlike yourself, contact a doctor urgently.

In some people, antidepressants can uncover or worsen symptoms of bipolar disorder or mania. This is uncommon, but important.

Tell your doctor if you have ever had periods of unusually high energy, reduced need for sleep, impulsive behaviour, racing thoughts or a diagnosis of bipolar disorder.

Common early side effects and what may help

Side effects vary from person to person. Some people have very few; others need extra support during the first couple of weeks.

Nausea or upset stomach

Nausea is one of the more common early side effects. It may improve after the first week or two.

Taking sertraline with or after food may help some people, unless your prescriber has advised otherwise. Small, bland meals and regular fluids may also help.

Diarrhoea or loose stools

Digestive changes can happen early on. Drink enough fluids, especially if you have diarrhoea.

Seek advice if diarrhoea is severe, persistent, contains blood, or you feel dehydrated. Our guide to dehydration symptoms may be useful if fluid loss is a concern.

Headache

Headaches may occur when starting sertraline and often settle. Drinking enough water, eating regularly and resting may help.

Ask a pharmacist or GP what pain relief is suitable for you, especially if you take other medicines.

Sleep changes

Some people feel sleepy; others feel more awake or restless. If sertraline affects your sleep, ask your prescriber or pharmacist whether changing the time you take it may help.

Do not change dose or timing if you have been given specific instructions without checking first.

Feeling jittery or more anxious

This can be distressing, especially if you already have anxiety. Gentle breathing exercises, reducing caffeine, avoiding energy drinks and keeping routines simple may help.

Contact your GP if anxiety feels severe, unmanageable or is getting worse.

Sexual side effects

Sertraline can affect sex drive, arousal, orgasm or erections. This can feel embarrassing to mention, but it is a known side effect and doctors hear about it often.

If it persists or affects your wellbeing or relationship, speak to your prescriber. Do not stop suddenly because of embarrassment.

Emotional numbness

Some people feel emotionally “muted” on SSRIs. This may mean less crying and less anxiety, but also less excitement, motivation or emotional range.

For others, this feeling may actually be part of depression rather than the medicine.

If emotional numbness is troubling or persistent, speak to your prescriber. They may review dose, timing, duration, therapy options or whether another medicine would suit you better.

Taking sertraline safely

Take sertraline exactly as prescribed. It is usually taken once a day, with or without food. Try to take it at the same time each day so it becomes part of your routine.

Practical tips include:

• use a daily reminder or phone alarm
• take it with a regular routine, such as breakfast or brushing your teeth
• avoid suddenly stopping without medical advice
• ask a pharmacist before taking new over-the-counter medicines or supplements
• limit alcohol, especially while you are adjusting
• keep follow-up appointments
• tell your prescriber about side effects honestly

If you forget a dose, follow the advice in the patient information leaflet or ask a pharmacist. Do not double up doses unless a healthcare professional tells you to.

Can you drink alcohol while taking sertraline?

Alcohol can worsen depression and anxiety, affect sleep, increase drowsiness, reduce judgement, and make side effects harder to interpret.

Some people feel more sedated or emotionally unstable when drinking on sertraline.

It is often sensible to avoid alcohol or keep it very limited while starting sertraline, especially during the first few weeks.

If alcohol is a regular coping strategy, mention this to your GP or mental health professional so they can support you safely.

Medicines and supplements to check first

Sertraline can interact with some medicines and supplements. Always check with a pharmacist, GP or prescriber before starting anything new.

This is especially important with:

• other antidepressants
• St John’s wort
• some migraine medicines
• some painkillers and anti-inflammatory medicines
• blood-thinning medicines
• some cold and flu remedies
• recreational drugs

Do not assume herbal products are automatically safe. St John’s wort, for example, can interact with antidepressants and increase the risk of side effects.

If you are unsure whether a medicine is safe to take with sertraline, a pharmacist can advise. Our guide to when to see a pharmacist instead of a GP explains when pharmacy advice can be helpful.

Sertraline, therapy and recovery

Medication and talking therapy can work well together. Sertraline may reduce symptom intensity, while therapy can help you understand patterns, build coping strategies, process experiences and make changes in daily life.

For depression and anxiety, options may include cognitive behavioural therapy, counselling, guided self-help, trauma-focused therapy, interpersonal therapy or other approaches depending on your needs.

If you are not sure what support is available, see our guides to self-referring to mental health services and mental health support options in the UK.

How you may know sertraline is working

Improvement may be gradual. You may not wake up one day feeling completely better. Instead, you may notice small signs that life is becoming more manageable.

Signs sertraline may be helping include:

• fewer panic attacks
• less intense anxiety
• fewer spiralling thoughts
• better sleep
• improved appetite
• more ability to concentrate
• less tearfulness
• more interest in daily life
• more ability to leave the house, work, study or socialise
• feeling more able to use coping strategies

Sometimes other people notice changes before you do. A partner, friend, family member or therapist may notice you seem calmer, more engaged or less overwhelmed.

What if sertraline does not work?

Sertraline does not work for everyone. If it does not help after a fair trial, or side effects are too difficult, your prescriber may discuss options.

These may include:

• continuing a little longer if improvement is starting
• adjusting the dose
• switching to another antidepressant
• adding or changing talking therapy
• reviewing diagnosis or other conditions
• checking sleep, alcohol, substances, medicines or physical health factors

Try not to see this as failure. Finding the right treatment can take time, and many people need adjustments before they find what works.

Do not stop sertraline suddenly

If you want to stop sertraline, speak to your prescriber first. Stopping suddenly can cause withdrawal or discontinuation symptoms, especially if you have been taking it for a while.

Symptoms may include:

• dizziness
• flu-like feelings
• irritability
• anxiety
• sleep disturbance
• headaches
• nausea
• unusual “electric shock” sensations

A gradual reduction plan can reduce the risk of these symptoms.

Do not stop suddenly because you feel better either. Feeling better may mean the medicine is helping. Your doctor can advise how long to continue based on your symptoms, history and risk of relapse.

When to book a review or get urgent help

Your prescriber should usually arrange a review after starting sertraline. This is particularly important if you are young, have severe symptoms, have had suicidal thoughts, have bipolar symptoms, are pregnant, have other health conditions, or are taking other medicines.

When to book a review sooner

Book a review sooner if:

• side effects feel severe or unbearable
• your mood or anxiety is getting worse
• you have thoughts of self-harm
• you feel unusually agitated, impulsive or restless
• you have symptoms of mania
• you have palpitations, fainting or chest pain
• you are not sure whether to continue
• you have started or stopped another medicine

If you need help arranging care, our guide to how to get a GP appointment quickly in the UK may help.

When to get urgent help

Most side effects are not emergencies, but some symptoms need urgent help.

Call 999 or go to A&E now if you:

• feel at immediate risk of harming yourself
• have taken an overdose
• have severe chest pain, severe breathlessness or collapse
• have a seizure
• have swelling of the lips, tongue, throat or face, or difficulty breathing
• feel extremely confused, very agitated, feverish, sweaty, shaky or have muscle stiffness

The last group of symptoms can be a warning sign of a rare but serious reaction called serotonin syndrome, especially if sertraline is combined with certain other medicines or drugs. If in doubt, seek urgent advice.

If you are having chest pain or severe palpitations, our guides to chest pain and heart palpitations may help you recognise urgent symptoms, but do not delay emergency care if symptoms are severe.

FAQ: starting sertraline

How long does sertraline take to work?

Some people notice early changes after one or two weeks, but it can take several weeks to feel a clearer benefit. Antidepressants can take up to eight weeks to work fully. Anxiety, OCD and PTSD symptoms may sometimes take longer to improve than sleep or appetite.

Can sertraline make anxiety worse at first?

Yes, some people feel more anxious, restless or jittery during the first couple of weeks. This often improves as the body adjusts, but you should contact your GP if anxiety feels severe, unmanageable or is getting worse.

What are common side effects in the first week?

Common early side effects include nausea, headache, dry mouth, diarrhoea, reduced appetite, sleep changes, sweating, tiredness, shakiness and feeling restless. Many early side effects improve after the first week or two.

Should I take sertraline in the morning or at night?

Sertraline is usually taken once a day. Some people prefer morning because it can affect sleep, while others take it later if it makes them sleepy. Follow your prescription instructions and ask a pharmacist or GP before changing the timing if you are unsure.

Can I drink alcohol while taking sertraline?

Alcohol can worsen depression and anxiety, disturb sleep, increase side effects and reduce judgement. It is often sensible to avoid alcohol or keep it very limited, especially while you are starting sertraline or adjusting the dose.

What should I do if sertraline makes me feel worse?

If you feel mildly worse but can cope, contact your GP or prescriber for advice and monitoring. If you feel at risk of harming yourself, feel unable to stay safe, or have suicidal thoughts, seek urgent help now by calling 999, going to A&E, contacting NHS 111, or calling Samaritans on 116 123.

Can I stop sertraline after a few days if I do not like it?

Do not stop sertraline suddenly without medical advice unless you have been told to do so because of a serious reaction. If side effects are difficult, contact your GP, prescriber or pharmacist. They can advise whether to continue, adjust timing, change dose or consider another option.

Does sertraline change your personality?

Sertraline should not change who you are. The aim is to reduce symptoms such as depression, anxiety, panic or intrusive thoughts. Some people feel emotionally muted or less reactive, which may need review if it is troubling or persistent.

What if I miss a dose of sertraline?

Follow the advice in your patient information leaflet or ask a pharmacist. In general, do not take a double dose to make up for a missed one unless a healthcare professional tells you to. If you miss doses often, a reminder or pill organiser may help.

When should I speak to a doctor after starting sertraline?

You should have a follow-up review after starting sertraline. Contact a doctor sooner if side effects are severe, your mood worsens, you have suicidal thoughts, you feel unusually agitated or impulsive, or you develop symptoms such as chest pain, fainting, severe confusion or a severe allergic reaction.

Final takeaway

The first weeks on sertraline can be a period of adjustment. Side effects such as nausea, headache, sleep changes, dry mouth or feeling jittery can appear before the benefits are clear. For many people, these early side effects improve after a couple of weeks.

Sertraline usually takes time. Some people notice small improvements within one or two weeks, but fuller benefits may take several weeks and sometimes up to eight weeks.

Keep taking it as prescribed unless a healthcare professional advises otherwise, and attend follow-up reviews.

Seek urgent help if you feel unsafe, have suicidal thoughts, take an overdose, have a severe allergic reaction, develop severe agitation or confusion, or have chest pain, fainting or severe breathlessness.

For official information, see the NHS guide to sertraline, the NHS guide to antidepressants, and the Royal College of Psychiatrists guide to antidepressants.

This article is for general information only and should not replace medical advice. Always take sertraline as prescribed. If you are worried about side effects, mood changes or safety, contact your GP, prescriber, NHS 111 or emergency services.