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Paroxetine

Brands and Forms

  • Paxil
    • tablet: 10mg scored, 20mg scored, 30mg, 40mg
    • oral suspension: 10mg/5ml
  • Paxil CR
    • controlled-release tablet: 12.5mg, 25mg, 37.5mg
  • Pexeva
    • tablet: 10mg scored, 20mg scored, 30mg, 40mg
  • Seroxat
  • Sereupin
  • Aropax
  • Deroxat
  • Rexetin
  • Xetanor
  • Paroxat

Uses of Paroxetine

Paroxetine is commonly used for treating Depressive Disorders (including Major Depressive Disorder, Dysthymia, and Premenstrual Dysphoric Disorder) and Anxiety Disorders (including Panic Disorder, Generalized Anxiety Disorder, Social Phobia, PTSD, and Obsessive-Compulsive Disorder).

It can also be used for treating Bulimia Nervosa, Binge-Eating Disorder, Hypochondriasis, Body Dysmorphic Disorder, Trichotillomania, Depression in Bipolar Disorder, and impulsive behaviors associated with Borderline Personality Disorder and Dementia.

How Paroxetine Works

Paroxetine is an SSRI antidepressant. It blocks serotonin reuptake at the serotonin transporter, and thus boosts serotonin actions in the central nervous system. Paroxetine also desensitizes serotonin 1a autoreceptors, is a mild antagonist at the histamine H1 receptor, and is a mild blocker of norepinephrine reuptake.

Cautions when Using Paroxetine

Paroxetine can induce Manic or Mixed Episodes and Rapid Cycling in people with Bipolar Disorder.

Children and adolescents who use antidepressants like Paroxetine may develop self-injurious or suicidal behaviors (for more information, see here).

Use with caution in people with a known seizure disorder, and in those who are taking anticoagulant (blood thinning) medication.

Long-term use of SSRI antidepressants like Paroxetine has been associated with increased risk of osteoporosis and bone fractures in individuals above age 50.

Paroxetine may have a higher rate of sexual side-effects than other SSRI antidepressants.

Paroxetine should not be used during or within 14 days following the administration of an MAOI, because a hypertensive crisis may result.

Do not combine Paroxetine with Thioridazine or Pimozide due to the risk of dangerous cardiac arrhythmias.

Dosing of Paroxetine

The usual therapeutic range of Paroxetine is 20-60mg/day; higher doses of 80-100mg/day may be required for Obsessive-Compulsive Disorder. It can be given once daily, either in the morning or at bedtime, though at bedtime may be preferred in cases where somnolence occurs as a side-effect.

Paroxetine is usually started at 10mg/day for a week, and then increased to 20mg/day. The dose can be raised by 10-20mg every week, though it is common practice to wait 4 weeks at 20mg/day for therapeutic effects to take place before deciding to increase the dose. Dose increases are usually done at 2-week intervals to allow time for therapeutic effects to appear.

When using Paxil CR, consider that 10mg of regular Paroxetine is equivalent to 12.5mg of Paxil CR.

When wanting to stop this medication, the dose should be decreased gradually over a period of 6-8 weeks. A sudden cessation of the medication can result in an SSRI discontinuation syndrome.

Onset of action

Therapeutic effects are not expected before 2-4 weeks at a dose of 20mg/day. If no significant effects are seen after 6-8 weeks of use, including at least 2 weeks at a dose above 20mg/day, then the medication may not work at all.

Kidney impairment

Use a lower therapeutic dose range of 10-40mg/day (12.5-50mg/day of Paxil CR).

Liver impairment

Use a lower therapeutic dose range of 10-40mg/day (12.5-50mg/day of Paxil CR).

Side-effects of Paroxetine

Below is a list of most of the reported side-effects of Paroxetine. Most of these side-effects occur in only a minority of individuals, and many also resolve with time while the medication is continued.

Cardiovascular: vasodilation; palpitations; hypertension; tachycardia; heart rate abnormalities (very rare).

Central Nervous System: somnolence; insomnia; tremor; fatigue; reduced or increased appetite; decreased libido (see below on managing sexual side-effects); dizziness; yawning; weakness; confusion; impaired concentration; headaches; paresthesia; fever; akathisia and other extrapyramidal symptoms (rare); seizures (very rare); serotonin syndrome (very rare).

Dermatologic: excessive sweating; itchiness; rash; hair loss (rare).

Endocrine/Metabolic: elevated prolactin (very rare); SIADH (very rare).

Eyes, Ears, Nose and Throat: blurred vision; abnormal vision; pharyngitis; rhinitis; tinnitus (ringing noises in ear).

Gastrointestinal: nausea; dry mouth; diarrhea; constipation; increased or decreased appetite; dyspepsia; vomiting; abdominal pain; flatulence; taste perversion; GI hemorrhage (rare, due to the blood-thinning effects of the medication); hepatitis (very rare); pancreatitis (very rare).

Genitourinary: abnormal ejaculation (see below on managing sexual side-effects); impotence; anorgasmia; dysmenorrhea; urinary frequency or hesitancy; urinary tract infection; priapism.

Hematologic: increases bleeding time (thins the blood); easy bruising; bone marrow suppression (very rare).

Muskuloskeletal: joint and muscle pain; risk of osteoporosis and bone fractures with long-term use of Paroxetine in individuals over age 50.

Psychiatric: anxiety; agitation; apathy; worsening depression; suicidal thoughts (overall, Paroxetine use helps to lower risk of suicide); self-injurious behaviors among children and adolescents; can induce Manic or Mixed Episodes and Rapid Cycling in people with Bipolar Disorder.

Respiratory: yawning; sinusitis.

Common side-effects of Paroxetine

Insomnia, somnolence, weakness, sexual side-effects (including erectile and ejaculation problems in men, and loss of libido and absent orgasm in men and women; see below on managing sexual side-effects), headache, tremor, dizziness, excessive sweating, nausea, dry mouth, diarrhea, constipation, decreased or increased appetite.

Rare but serious side-effects of note of Paroxetine

  • Children and adolescents who use antidepressants like Paroxetine may develop self-injurious or suicidal behaviors (for more information, see here).
  • Seizures

SSRI discontinuation syndrome

Individuals who suddenly stop using Paroxetine after taking the medication at moderate or high doses over a significant period of time are at risk of developing a discontinuation syndrome, which can include the following symptoms: dizziness, electric shock-like sensations, sweating, nausea, insomnia, tremor, anxiety, restlessness, agitation, depressed mood, irritability, confusion, lethargy, and vertigo. These symptoms usually start anywhere from one day to one week after the medication was stopped, and can persists for days or even weeks.

This syndrome can be treated by restarting the medication at its prior dose. It can be prevented by decreasing the dose gradually over a period of 6-8 weeks when wanting to stop the medication. In rare cases, individuals may experience the discontinuation syndrome even when the medication is being tapered gradually; in such cases, an extremely slow and gradual taper will be necessary.

Managing sexual side-effects of Paroxetine

The first step to manage this is to try to lower the dose of the Paroxetine. If this is not possible, or is not an effective solution, then either Bupropion, or Sildenafil (Viagra) or Vardenafil (Levitra), can be added [ref]. (Sildenafil and Vardenafil can be effective for female sexual side-effects as well, including difficulty achieving orgasm [ref, ref]).

Bupropion and Mirtazepine are two antidepressants that tend to have very low rates of sexual side-effects.

Paroxetine overdose

Confusion, dizziness, nausea, somnolence, tachycardia, tremor, vomiting, coma.

Paroxetine and pregnancy

Category D: some studies have shown adverse effects to human fetuses; should only be used in pregnancy if clearly needed and if benefits outweigh potential risks. For further information, see the section on treating Depression in pregnancy.

Medical Monitoring for Paroxetine

None for healthy individuals.

Drug Interactions with Paroxetine

  • Caution should be used when combining Paroxetine with other medications that can increase bleeding time and reduce blood clotting, including Aspirin, NSAIDs, anti-platelet agents, Heparin and Coumadin.
  • Combination with other serotonergic medications, including SSRI antidepressants, could potentially precipitate a serotonin syndrome.
  • Paroxetine should not be used during or within 14 days following the administration of an MAOI, because a hypertensive crisis may result.
  • Do not combine Paroxetine with Thioridazine or Pimozide due to the risk of dangerous cardiac arrhythmias.
  • Paroxetine can rarely cause weakness, hyperreflexia and incoordination when combined with Sumatriptan or other triptans.
  • Paroxetine blood concentrations can be increased by Cimetidine.
  • Paroxetine blood concentrations can be decreased by Fosamprenavir, Ritonavir, Phenobarbital, Phenytoin.
  • Paroxetine may elevate blood concentrations of Cyclosporine, Warfarin, Theophylline, Tricyclic Antidepressants, Atomoxetine, some beta blockers, Risperidone, type IC antiarrhythmics.
  • Paroxetine may decrease blood concentrations of Digoxin, Phenytoin.
  • Paroxetine can reduce the effects of Zolpidem.