PAROXETINE (Paxil): What is used for?

What is Paroxetine?

Paroxetine (Paroxetina) is a drug used for the treatment of depression, anxiety and obsessive compulsive disorder. The product ingredients are: Paroxetine hydrochloride (hcl), Paroxetine hydrochloride hemihydrate, Paroxetine mesylate.

The brand names of Paroxetine in the United States are: Paxil, Paxil CR, Brisdelle and Pexeva.

Mechanism of action of Paroxetine

It specifically inhibits the reuptake of 5-hydroxytryptamine by brain neurons.

Therapeutic indications uses, benefits and dosage of Paroxetine

Oral dose, 1 time/day, in the morning with food.

Major depressive episode: recommended: 20 mg/day, at 3-4 weeks check and adjust if necessary, max. 50 mg/day increasing 10 mg according to response. Continue the treatment for at least 6 months, until the patient is free of symptoms.

Obsessive-compulsive disorder: recommended: 40 mg/day. Start at 20 mg/day, increasing gradually, with increments of 10 mg to 40 mg. Max: 60 mg/day.

Anxiety disorder with and without agoraphobia: recommended: 40 mg/day. Start at 10 mg/day, increasing gradually with increments of 10 mg to 40 mg. Max: 60 mg/day.

Social anxiety disorder/social phobia. Generalized anxiety disorder. Post-traumatic stress disorder: recommended: 20 mg/day, if necessary increase to max. 50 mg/day with increments of 10 mg.

In severe renal insufficiency and in hepatic insufficiency it is necessary to reduce the dose to the lower limit of the dosage range. It should not be used in < 18 years.

Mode of administration of Paroxetine

Oral use.

Tablets: 1 time/day, in the morning with food; swallow, do not chew.
Oral drops in solution: 1 time/day, in the morning with food. Dilute in a little water.

Contraindications of Paroxetine

  • Hypersensitivity to paroxetine.
  • Combination with MAOI, start treatment two weeks after interruption of irreversible MAOI, or 24 h after interruption of reversible MAOI, and at least one week elapse between interruption of paroxetine and initiation of MAOI.
  • Combination with thioridazine or pimozide.

Warnings and Precautions with Paroxetine

History of mania, severe renal failure, liver failure, diabetes (if receiving paroxetine and concomitant pravastatin, may require dose adjustment of oral hypoglycaemic and/or insulin), epilepsy, seizures, ECT, closed-angle or antecedent glaucoma, heart disease, situations leading to hyponatremia, history of bleeding disorders or bleeding predisposing states, elderly.

Concomitant use with oral anticoagulants, drugs that affect platelet function and increase risk of bleeding.
Combined with serotonergic and/or neuroleptic risk of MNS.

Children and adolescents, should not be used, in case it was necessary to extreme vigilance since it increases risk of suicidal behavior and hostility; in children < 7 years there are no studies.
Acatasia/psychomotor agitation may appear at 1 a.m., evaluate its use.

Risk of suicide, follow the patient closely until improvement is detected; patients with a history of suicidal behaviour or thoughts, or those who show a significant degree of suicidal ideation before the start of treatment, are at greater risk and should be subject to greater vigilance. Sudden interruption of treatment may result in withdrawal symptoms, which should be done gradually over several weeks or months.

Liver failure

Caution. Reduce dose to the lower limit of the therapeutic range.

Kidney failure

Caution in renal failure with Clcr < 30 ml/min. Reduce dose to the lower limit of the therapeutic range.

Interactions with Paroxetine

  • Potentiation of toxicity (serotonergic syndrome) with: MAOI, L-tryptophan, triptans, tramadol, linezolid, methylthionine chloride, SSRI, lithium, pethidine, Hypericum perforatum.
  • Plasma levels decreased by: fosamprenavir/ritonavir.
  • Increases plasma levels of: procyclidine, clomipramine, nortriptyline, desipramine, perfenazine, thioridazine, risperidone, atomoxetine, propafenone, flecainide, metoprolol.
  • Increases activity and risk of bleeding with: oral anticoagulants, NSAIDs and other antiplatelet agents.
  • Avoid alcohol consumption.
  • Reduces effectiveness of: tamoxifen. The administration of paroxetine during breast cancer prevention with tamoxifen should be avoided whenever possible.
  • Caution with: fentanyl in general anesthesia or in tto. chronic pain.
  • Co-administration of paroxetine and pravastatin may result in increased blood glucose levels.

Pregnancy and Paroxetine

Risk of cardiovascular malformations in neonates during the first trimester of pregnancy.
Use only when strictly indicated.
To evaluate newborns if the mother uses paroxetine in the late stages of pregnancy, due to risk of: respiratory failure, cyanosis, apnoea, convulsions, thermal instability, feeding difficulties, vomiting, hypoglycaemia, hypertonia, hypotonia, hyperreflexia, tremors, nervousness, irritability, lethargy, constant crying, drowsiness and difficulty sleeping.


Compatible. Small amounts are excreted, serum concentrations were undetectable.
Maintaining lactation could be considered, as no effect on the child is expected.

Effects on driving ability

Paroxetine can cause sedation, dizziness. Therefore, patients should be advised that if they experience sedation or dizziness, they should avoid performing potentially hazardous tasks, such as driving or using machines.

Adverse reactions and side effects of Paroxetine

Increased cholesterol levels, decreased appetite; drowsiness, insomnia, agitation, aggressiveness, abnormal dreams; decreased concentration, dizziness, tremors, headache, altered concentration.
Blurred vision; yawning; nausea, constipation, diarrhea, vomiting, dry mouth; sweating; sexual dysfunction; asthenia, weight gain.
Unknown frequency: bruxism.

Short-term clinical trials in children and adolescents showed an increase in suicidal behaviour, self-harming behaviour and increased hostility.


Source: The content of this active ingredient has been written taking into account the clinical and molecular information of all medicines authorised and marketed in the United States under the Unique Ingredient Identifier (UNII) by the Substance Registration System (SRS) of the Food and Drug Administration (FDA) and the United States Pharmacopeia (USP).

In order to know in detail the information authorized by the FDA for each drug, you should consult the corresponding medication guide authorized by the FDA.


UNII: 41VRH5220H
PubChem CID: 43815
NCI Thesaurus: C61879

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