Paroxetine

Is paroxetine safe?

For most adults it is an effective and reasonably safe antidepressant, but it has more drawbacks than the other common SSRIs. Paroxetine, sold as Paxil in the US and Seroxat in the UK, treats depression, obsessive-compulsive disorder, panic disorder, social anxiety, generalised anxiety and PTSD. It is not addictive, and like other SSRIs it is far less dangerous in overdose than older tricyclic antidepressants.

The catches are specific. Stopping it is often harder than with other SSRIs. It blocks a liver enzyme that clears many common drugs. Early-pregnancy use is linked to heart defects. And in trials more people quit it because of side effects. We score it 63, below sertraline (72) and escitalopram (71) and above venlafaxine (59).

Paroxetine withdrawal: the main problem

Paroxetine has a half-life of about 21 hours, and its levels are not proportional to dose, because it saturates CYP2D6CYP450 enzymesA family of liver enzymes that break down many medicines. When another drug or supplement speeds them up or slows them down, drug levels change.More in the glossary, one of the enzymes that clears it, so blood levels fall steeply at lower doses. The UK label even notes very rare reports of symptoms after a single missed dose. The UK Seroxat label reports withdrawal symptoms in 30% of people after stopping paroxetine in trials, against 20% after stopping placebo. The usual ones are dizziness, electric-shock sensations, vivid dreams, poor sleep, agitation, nausea, tremor, sweating and confusion.

A 2024 meta-analysis in the Lancet Psychiatry, covering 79 studies, found that paroxetine was among the antidepressants linked to more severe discontinuation symptoms, alongside imipramine and desvenlafaxine or venlafaxine; it was the only SSRI in that group. The UK label says symptoms usually pass within two weeks, though in some people they last two to three months or more.

What helps: never stop abruptly, and plan a slow reduction with your prescriber. The US label used a cut of 10 mg a day each week, followed by a week at 20 mg. Many people need smaller steps at the end, which may mean a liquid form or lower-strength tablets.

Side effects: why more people stop

Paroxetine is more sedating and has more anticholinergic effects (dry mouth, constipation, blurred vision) than other SSRIs. In the Paxil label's six-week depression trials:

One in five people in those trials stopped because of side effects. Sexual problems are common and often persist while on the drug; paroxetine is one of the medicines the MHRA named in October 2026 when it said UK leaflets will mention post-SSRI sexual dysfunction (PSSD), in which symptoms continue after stopping. The label also notes that paroxetine may affect sperm quality.

The rest are the standard SSRI risks: serotonin syndromeSerotonin syndromeA reaction caused by too much serotonin in the body, usually from combining medicines that raise it. Symptoms range from shivering to high fever.More in the glossary, bleeding (more so with aspirin, ibuprofen or warfarin), low sodium in older people, mania in bipolar disorder, seizures in 0.1% of trial patients, and angle-closure glaucoma.

Pregnancy and paroxetine

This is where paroxetine differs from its relatives on paper. The current US label carries a warning that paroxetine can cause fetal harm: meta-analyses link first-trimester use to a less than twofold rise in heart malformations, with about 2 to 2.5 times the risk of right ventricular outflow tract defects. The background risk of major birth defects is 2% to 4%, so the absolute increase is small, and the studies have limits. The label says that for women planning a pregnancy or in the first trimester, paroxetine should be started only after other options have been considered.

Late in pregnancy, SSRIs including paroxetine are linked to breathing and feeding problems in some newborns, persistent pulmonary hypertension of the newborn, and a small rise in heavy bleeding after birth. None of this means someone already taking it should stop on their own: relapse of depression in pregnancy is common after stopping, and abrupt withdrawal is unpleasant. Talk to your doctor or midwife.

Interactions: a strong CYP2D6 blocker

Paroxetine strongly and irreversibly blocks CYP2D6CYP450 enzymesA family of liver enzymes that break down many medicines. When another drug or supplement speeds them up or slows them down, drug levels change.More in the glossary, the liver enzyme that clears many medicines. That changes the dose of drugs such as tricyclic antidepressants, metoprolol, some antipsychotics and atomoxetine, and stops codeine and tramadol from being turned into their active forms. The US label contraindicates paroxetine with QT-prolongingQT prolongationA delay in the heart's electrical recovery between beats, seen on an ECG. Some medicines cause it, and in rare cases it leads to a serious heart rhythm problem.More in the glossary drugs cleared by CYP2D6, and the UK label names thioridazine and pimozide.

The most serious example is tamoxifen. Paroxetine can lower levels of endoxifen, tamoxifen's active form, and some studies found worse breast cancer outcomes. Both labels advise another antidepressant for women on tamoxifen. Like every SSRI it is contraindicatedContraindicationA situation in which a medicine should not be used, because the risk clearly outweighs any benefit, such as a known allergy to it.More in the glossary with MAOIs, linezolid and IV methylene blue.

Teenagers, Study 329 and the regulatory record

Paroxetine has a history. Study 329, a trial of paroxetine in 275 teenagers published in 2001, was reanalysed from the full data in the BMJ in 2015: it found no benefit over placebo and clear increases in harms, including suicidal thoughts and behaviour. The UK label says paroxetine should not be used in under-18s, and it is not approved for them in the US. In 2012 GlaxoSmithKline agreed to plead guilty in the US to criminal charges that included misbranding Paxil, as part of a $3 billion settlement. The US Justice Department said the company had promoted Paxil for depression in under-18s from 1998 to 2003, although it was never approved for them.

More recently, Apotex recalled 6,972 bottles of Paxil CR 37.5 mg in August 2026 for failing dissolution tests, and a generic 37.5 mg extended-release tablet followed in September (both Class II, the middle level of FDA recall severity).

Overdose

Paroxetine alone rarely kills. In a study of England and Wales from 2000 to 2006, SSRIs other than citalopram had a case fatality ratio of 0.3, against 13.8 for tricyclics. The label still lists delayed seizures, coma and changes in heart rhythm. Any overdose needs medical assessment: in the US call Poison Help on 1-800-222-1222; in the UK call 111, or 999 if someone is drowsy, fitting or has palpitations.

How we scored it

Overdose marginOverdose marginHow far a normal dose is from a harmful one. A wide margin means an accidental extra dose is unlikely to cause serious harm.More in the glossary (78) and track record (90) are strong. Interactions (46) are its weakest factor because of CYP2D6CYP450 enzymesA family of liver enzymes that break down many medicines. When another drug or supplement speeds them up or slows them down, drug levels change.More in the glossary, and dependence (60) reflects withdrawal that a 2024 meta-analysis ranked as the most severe among SSRIs. Regulatory warnings (40) reflect the boxed warningBoxed warningThe strongest safety warning the US FDA puts on a medicine's label, printed inside a black border at the top.More in the glossary, the pregnancy warning, the UK under-18 advice and the 2026 recalls. A lower score is not a reason to stop a medicine that is working; changes should be planned with your prescriber.