How does this medication work? What will it do for me?

Paroxetine belongs to the class of medications called selective serotonin reuptake inhibitors (SSRIs). It is used to treat depression, obsessive-compulsive disorder, panic disorder, social phobia (social anxiety disorder), generalized anxiety disorder, and post-traumatic stress disorder. It works by affecting the balance of chemicals in the brain that are associated with depression and anxiety disorders.

It may take several weeks before the full beneficial effects of this medication are felt. Continue taking the medication until you have consulted with your doctor, even if you feel your symptoms are not improving.

This medication may be available under multiple brand names and/or in several different forms. Any specific brand name of this medication may not be available in all of the forms or approved for all of the conditions discussed here. As well, some forms of this medication may not be used for all of the conditions discussed here.

Your doctor may have suggested this medication for conditions other than those listed in these drug information articles. If you have not discussed this with your doctor or are not sure why you are taking this medication, speak to your doctor. Do not stop taking this medication without consulting your doctor.

Do not give this medication to anyone else, even if they have the same symptoms as you do. It can be harmful for people to take this medication if their doctor has not prescribed it.

What form(s) does this medication come in?

ratio-Paroxetine is no longer being manufactured for sale in Canada. For brands that may still be available, search under paroxetine. This article is being kept available for reference purposes only. If you are using this medication, speak with your doctor or pharmacist for information about your treatment options.

How should I use this medication?

For adults being treated for depression, the recommended starting dose is 20 mg taken once daily. This is also the dose that most people find effective. If necessary, your doctor may suggest you increase the dose slowly to a maximum of 50 mg daily.

For people being treated for obsessive-compulsive disorder, the usual starting dose of paroxetine is 20 mg taken once daily. Gradually, your doctor will have you increase the dose to the recommended dose of 40 mg daily. If necessary, the dose may be increased to a maximum of 60 mg daily.

For people being treated for panic disorder, the usual starting dose is 10 mg once daily. It should then be slowly increased to the recommended dose of 40 mg daily. If necessary, the dose may be increased to a maximum of 60 mg daily.

For social phobia (social anxiety disorder), generalized anxiety disorder and post traumatic stress disorder, the starting dose is 20 mg taken once daily. The maximum dose for treating any of these conditions is 50 mg daily.

Many things can affect the dose of medication that a person needs, such as body weight, other medical conditions, and other medications. If your doctor has recommended a dose different from the ones given here, do not change the way that you are taking the medication without consulting your doctor.

In all cases, this medication is usually taken first thing in the morning. It may be taken with or without food. Swallow the tablet whole – do not chew or crush it.

It is important that this medication be taken exactly as prescribed by your doctor. If you miss a dose, take it as soon as possible and continue with your regular schedule. If it is almost time for your next dose, skip the missed dose and continue with your regular dosing schedule. Do not take a double dose to make up for a missed one. If you are not sure what to do after missing a dose, contact your doctor or pharmacist for advice.

Store this medication at room temperature and keep it out of the reach of children.

Do not dispose of medications in wastewater (e.g. down the sink or in the toilet) or in household garbage. Ask your pharmacist how to dispose of medications that are no longer needed or have expired.

Who should NOT take this medication?

Do not take paroxetine if you:

  • are allergic to paroxetine or any ingredients of the medication
  • are taking an MAO inhibitor (e.g., phenelzine, tranylcypromine, moclobemide) or have taken a MAO inhibitor within the past 2 weeks (do not start treatment with an MAO inhibitor until at least 2 weeks after stopping paroxetine treatment)
  • take pimozide
  • take thioridazine

What side effects are possible with this medication?

Many medications can cause side effects. A side effect is an unwanted response to a medication when it is taken in normal doses. Side effects can be mild or severe, temporary or permanent. The side effects listed below are not experienced by everyone who takes this medication. If you are concerned about side effects, discuss the risks and benefits of this medication with your doctor.

The following side effects have been reported by at least 1% of people taking this medication. Many of these side effects can be managed, and some may go away on their own over time.

Contact your doctor if you experience these side effects and they are severe or bothersome. Your pharmacist may be able to advise you on managing side effects.

  • constipation
  • decreased appetite
  • decreased sexual desire or ability
  • diarrhea
  • dizziness
  • drowsiness
  • dry mouth
  • headache
  • increased sweating
  • nausea
  • nervousness
  • nightmares
  • tremor
  • trouble sleeping
  • unusual tiredness or weakness
  • vomiting
  • yawning

Although most of these side effects listed below don't happen very often, they could lead to serious problems if you do not check with your doctor or seek medical attention.

Check with your doctor as soon as possible if any of the following side effects occur:

  • agitation
  • feelings of paranoia
  • increased cholesterol levels
  • muscle pain or weakness
  • new or worsening signs of depression (such as feeling sad, losing interest in things you used to enjoy, weight changes, changes in sleep habits, feelings of guilt or worthlessness, thoughts of suicide)
  • problems with urination
  • restless legs syndrome (irresistible urge to move the legs)
  • signs of bleeding (e.g., bloody nose, blood in urine, coughing blood, bleeding gums, cuts that don't stop bleeding)
  • signs of liver problems (e.g., nausea, vomiting, diarrhea, loss of appetite, weight loss, yellowing of the skin or whites of the eyes, dark urine, pale stools)
  • skin rash
  • symptoms of glaucoma (e.g., eye pain, blurred vision)
  • symptoms of low blood sodium (confusion, seizures, drowsiness, dryness of mouth, increased thirst, lack of energy)
  • talking, feeling, and acting with excitement and activity you cannot control

Stop taking the medication and seek immediate medical attention if any of the following occur:

  • chest pain
  • erection without sexual stimulation accompanied by pain or tenderness, lasting for several hours
  • seizure or convulsions
  • serotonin syndrome (signs include agitation, confusion, diarrhea, fever, overactive reflexes, poor coordination, restlessness, shivering, sweating, talking or acting with excitement you cannot control, trembling or shaking, twitching)
  • signs of bleeding in the stomach (e.g., bloody, black, or tarry stools, spitting up of blood, vomiting blood or material that looks like coffee grounds)
  • signs of a severe skin reaction such as blistering, peeling, a rash covering a large area of the body, a rash that spreads quickly, or a rash combined with fever or discomfort
  • thoughts of suicide or hurting yourself

Some people may experience side effects other than those listed. Check with your doctor if you notice any symptom that worries you while you are taking this medication.

Are there any other precautions or warnings for this medication?

Before you begin using a medication, be sure to inform your doctor of any medical conditions or allergies you may have, any medications you are taking, whether you are pregnant or breast-feeding, and any other significant facts about your health. These factors may affect how you should use this medication.

Abnormal bleeding: Paroxetine, like other similar medications, may cause abnormal bleeding, including bleeding in the stomach or intestines. People who have or have had a history of bleeding disorders should discuss with their doctor how this medication may affect their medical condition, how their medical condition may affect the dosing and effectiveness of this medication, and whether any special monitoring is needed.

Report any unusual bruising or bleeding to your doctor, especially if you are taking other medications that affect blood clotting. These medications include acetylsalicylic acid (ASA), clopidogrel, dipyridamole, nonsteroidal anti-inflammatory drugs (NSAIDs; e.g., ibuprofen or naproxen), other anticoagulant medications (e.g., warfarin), and certain antipsychotic medications.

Drowsiness/reduced alertness: Although paroxetine is not known to cause drowsiness, it is advisable to avoid driving or operating hazardous machinery until you determine how paroxetine affects your ability to do these things safely.

Glaucoma: Paroxetine can cause an increase in the pressure in the eye, making symptoms of glaucoma worse. If you have narrow-angle glaucoma, discuss with your doctor how this medication may affect your medical condition, how your medical condition may affect the dosing and effectiveness of this medication, and whether any special monitoring is needed.

Heart disease: If you have heart disease, discuss with your doctor how this medication may affect your medical condition, how your medical condition may affect the dosing and effectiveness of this medication, and whether any special monitoring is needed.

Kidney function: People with kidney disease may need lower doses of this medication. If you have kidney disease or reduced kidney function, discuss with your doctor how this medication may affect your medical condition, how your medical condition may affect the dosing and effectiveness of this medication, and whether any special monitoring is needed.

Liver function: Liver disease or reduced liver function may cause this medication to build up in the body, causing side effects. If you have liver problems, discuss with your doctor how this medication may affect your medical condition, how your medical condition may affect the dosing and effectiveness of this medication, and whether any special monitoring is needed. Your doctor may want to test your liver function regularly with blood tests while you are taking this medication.

If you experience symptoms of liver problems such as fatigue, feeling unwell, loss of appetite, nausea, yellowing of the skin or whites of the eyes, dark urine, pale stools, abdominal pain or swelling, and itchy skin, contact your doctor immediately.

Mania: Paroxetine may cause symptoms of mania to worsen or return. If you have a history of mania or bipolar disorder, discuss with your doctor how this medication may affect your medical condition, how your medical condition may affect the dosing and effectiveness of this medication, and whether any special monitoring is needed.

Seizures: If you have a history of seizures, discuss with your doctor how this medication may affect your medical condition, how your medical condition may affect the dosing and effectiveness of this medication, and whether any special monitoring is needed. Anyone who develops seizures should seek immediate medical attention.

Serotonin Syndrome: Severe reactions are possible when paroxetine is combined with other medications that act on serotonin, such as tricyclic antidepressants, "triptan" medications for migraine and some medications to treat nausea due to chemotherapy. These combinations should be avoided. Symptoms of a reaction may include muscle rigidity and spasms, difficulty moving, changes in mental state including delirium and agitation. Coma and death are possible.

If you are taking other medications that affect serotonin, discuss with your doctor how this medication may affect your medical condition, how your medical condition may affect the dosing and effectiveness of this medication, and whether any special monitoring is needed.

Stopping the medication: Stopping this medication suddenly may lead to side effects such as dizziness, abnormal dreams, numbness or tingling sensations, agitation, anxiety, nausea, vomiting, sweating, or other symptoms. If you are thinking of stopping the medication, check with your doctor first. Your doctor may want you to decrease the dose of the medication gradually when it is time to stop taking paroxetine.

Suicidal or agitated behaviour: People taking this medication may feel agitated (restless, anxious, aggressive, emotional, and feeling not like themselves), or they may want to hurt themselves or others. These behavioural changes may be more likely to occur in children and adolescents, however they are possible for all age groups that use this medication. These symptoms may occur within several weeks after starting this medication. If you experience these side effects or notice them in a family member who is taking this medication, contact your doctor immediately. You should be closely monitored by your doctor for emotional and behaviour changes while taking this medication.

Pregnancy: This medication should not be used during pregnancy unless the benefits outweigh the risks. Paroxetine has been reported to cause an increase in birth defects, primarily of the heart, in babies born to women who have taken it in the first trimester. It has also been reported that babies born to women who took medications of this kind during the last trimester of their pregnancy may experience adverse effects (such as breathing problems, seizures, trouble feeding, vomiting, low blood sugar, shaking, jitteriness, irritability, and constant crying) that result in an increase in the length of hospital stay. If you become pregnant while taking this medication, contact your doctor immediately.

Breast-feeding: This medication passes into breast milk. If you are a breast-feeding mother and are taking paroxetine, it may affect your baby. Talk to your doctor about whether you should continue breast-feeding.

Children and adolescents: The safety and effectiveness of paroxetine for those less than 18 years of age have not been established. The use of this medication by children and adolescents less than 18 years old may cause behavioural and emotional changes, such as suicidal thoughts and behaviour.

Seniors: Seniors may need lower doses of this medication, and they should be closely monitored by their doctor when taking paroxetine.

What other drugs could interact with this medication?

There may be an interaction between paroxetine and any of the following:

  • acarbose
  • acetylsalicylic acid (ASA)
  • alcohol
  • alfuzosin
  • alteplase
  • amiodarone
  • amphetamines (e.g., dextroamphetamine, lisdexamphetamine, methamphetamine)
  • antihistamines (e.g., diphenhydramine, hydroxyzine)
  • antipsychotic medications (e.g., chlorpromazine, haloperidol, olanzapine, quetiapine, risperidone)
  • atomoxetine
  • benzodiazepines (e.g., alprazolam, diazepam, lorazepam)
  • beta-blockers (e.g., carvedilol, metoprolol, propranolol)
  • bromocriptine
  • bupropion
  • buspirone
  • carbamazepine
  • celecoxib
  • certain antiarrhythmic medications (e.g., disopyramide, flecainide, propafenone,)
  • chloroquine
  • cimetidine
  • cincalcet
  • clopidogrel
  • clozapine
  • cyclophosphamide
  • dabigatran
  • dasatinib
  • desmopressin
  • dextromethorphan
  • efavirenz
  • galantamine
  • glucosamine
  • glyburide
  • imatinib
  • insulin
  • irinotecan
  • isoniazid
  • lithium
  • losartan
  • macrolide antibiotics (e.g., clarithromycin, erythromycin)
  • MAO inhibitors (e.g., linezolid, moclobemide, phenelzine, selegiline, tranylcypromine)
  • metoclopramide
  • metyrosine
  • mexilitine
  • mifepristone
  • mirtazapine
  • multivitamins/minerals
  • narcotic pain relievers (e.g., codeine, fentanyl, methadone, morphine, oxycodone)
  • nefazodone
  • nonsteroidal anti-inflammatory medications (NSAIDs; diclofenac, ibuprofen, naproxen)
  • omega-3 fatty acids
  • peginterferon Alfa-2b
  • pentoxifylline
  • pimozide
  • pioglitazone
  • pravastatin
  • promethazine
  • quinidine
  • quinine
  • quinolone antibiotics (e.g., levofloxacin, moxifloxacin)
  • rasagiline
  • repaglinide
  • rivaroxaban
  • other selective serotonin reuptake inhibitors (SSRIs; e.g., citalopram, fluoxetine, sertraline)
  • 5-HT3 antagonists (e.g., granisetron, ondansetron)
  • St. John's wort
  • tamoxifen
  • terbinafine
  • thioridazine
  • ticlopidine
  • tramadol
  • trazodone
  • certain tricyclic antidepressants (e.g., nortriptyline, amitriptyline, imipramine, desipramine)
  • "triptan" migraine medications (e.g., sumatriptan, zolmitriptan, rizatriptan)
  • tryptophan
  • vitamin E
  • warfarin

If you are taking any of these medications, speak with your doctor or pharmacist. Depending on your specific circumstances, your doctor may want you to:

  • stop taking one of the medications,
  • change one of the medications to another,
  • change how you are taking one or both of the medications, or
  • leave everything as is.

An interaction between two medications does not always mean that you must stop taking one of them. Speak to your doctor about how any drug interactions are being managed or should be managed.

Medications other than those listed above may interact with this medication. Tell your doctor or prescriber about all prescription, over-the-counter (non-prescription), and herbal medications that you are taking. Also tell them about any supplements you take. Since caffeine, alcohol, the nicotine from cigarettes, or street drugs can affect the action of many medications, you should let your prescriber know if you use them.