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SSRI (Selective Serotonin Reuptake Inhibitor)

Paroxetine

Brand names: Seroxat

Paroxetine is a selective serotonin reuptake inhibitor (SSRI) used for depression and a range of anxiety disorders, including generalised anxiety, panic disorder, social anxiety, obsessive-compulsive disorder and post-traumatic stress disorder.

Dosing — being independently re-sourced

ClinCalc Pro is rebuilding its dose data from primary open sources — the manufacturer SmPC (eMC), the WHO Model Formulary and other official references — under clinician review. This drug's structured dose is not yet published here. Confirm all doses against the product SmPC and your local formulary before prescribing.

US labelling (FDA)

Reference — US labelling, may differ from UK

Recommended starting and maximum daily dosage for MDD, OCD, PD, and PTSD: ( 2.2 ) Indication Starting Daily Dose Maximum Daily Dose MDD 20 mg 50 mg OCD 20 mg 60 mg PD 10 mg 60 mg PTSD 20 mg 50 mg Recommended starting dosage for SAD and GAD is 20 mg daily. ( 2.3 ) Elderly patients, patients with severe renal impairment or severe hepatic impairment: Starting dosage is 10 mg daily. Maximum dosage is 40 mg daily. ( 2.4 ) When discontinuing paroxetine tablets, reduce dosage gradually. ( 2.6 , 5.7 ) 2.1 Administration Information Administer paroxetine tablets as a single daily dose in the morning, with or without food. 2.2 Recommended Dosage for MDD, OCD, PD, and PTSD The recommended starting …

Source: US FDA prescribing information (openFDA / DailyMed), label dated 2026-04-16. Accessed 2026-06-12. US dosing and indications can differ from UK practice — use UK sources for prescribing decisions.

Clinical monograph

How it works

It selectively inhibits the reuptake of serotonin (5-HT) at the presynaptic neuronal membrane, increasing serotonergic neurotransmission. It is among the more potent SSRIs and also has modest anticholinergic activity.

Prescribing in practice

  • Paroxetine has a short half-life and no active metabolite, so it is particularly associated with discontinuation symptoms — withdraw by gradual dose tapering rather than stopping abruptly.
  • It tends to cause more sedation, anticholinergic effects and weight gain than some other SSRIs, and carries a risk of hyponatraemia and increased gastrointestinal bleeding (greater with concomitant NSAIDs or anticoagulants).
  • Generally avoided in pregnancy because of a signal for first-trimester cardiac malformations; consult current prescribing references and the SPC if treatment in pregnancy is being considered.

Monitoring

Monitor mood, anxiety and for emergence of suicidal ideation, especially early in treatment and in younger adults. Watch for hyponatraemia (particularly in older patients) and signs of bleeding. Review for serotonin syndrome if combined with other serotonergic agents.

Counselling the patient

  • Do not stop this medicine suddenly — speak to your prescriber so the dose can be reduced gradually to limit withdrawal effects such as dizziness, electric-shock sensations and irritability.
  • It may take a few weeks to work, and you may feel more anxious or restless at first — seek advice urgently if you have thoughts of harming yourself.
  • Tell your prescriber if you are pregnant or planning pregnancy, and report any unusual bruising or bleeding.

Evidence & guidelines

Guideline-recommended option for depression and anxiety disorders (NICE), though discontinuation symptoms can be more pronounced than with longer-acting SSRIs.

Reference: NICE CG90 (Depression); MHRA SSRIs in Paediatrics Safety Update; Drug verified in RxNorm (NLM); confirm dosing against the manufacturer SPC (eMC). Verify against your local formulary and current prescribing references before prescribing. Monograph status: clinician-reviewed (2026-07-04).

Related

Curated clinical cross-links plus same-class fallbacks.

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