Paroxetine (Paxil): dosage, uses, side effects

If you've been diagnosed with depression or another mental health condition, your healthcare provider may prescribe paroxetine or Paxil. This antidepressant works to balance your depressed mood and many other conditions. Learn about paroxetine's effectiveness, how to take it, and what to look out for so you can feel better.

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Paroxetine is an antidepressant medicine that helps balance your mood. The brand names for paroxetine are Paxil, Paxil CR, Pexeva, and Brisdelle. These medications come as tablets or in liquid form. Paxil CR is a controlled or extended-release tablet that slowly releases the drug into the body (NAMI, 2020).

Paroxetine, Paxil, and Pexeva are approved to treat (NAMI, 2020): 

• Major depressive disorder (MDD)—feeling sad, worthless, with a loss of interest or pleasure in daily activities

• Social anxiety disorder (social phobia)—fear of judgment and anxiety when interacting with others

• Panic disorder—unpredictable and sudden attacks of extreme worry and fear

• Generalized anxiety disorder (GAD)—constant, excessive, and uncontrolled worry

• Obsessive-compulsive disorder (OCD)—continual bothersome thoughts and the need for repetitive actions or compulsions 

• Post-traumatic stress disorder (PTSD)—fear and anxiety that happens after a traumatic event

Paxil CR is approved for most of the above, plus premenstrual dysphoric disorder (PMDD) for bothersome physical and mental symptoms that occur before a menstrual period (NAMI, 2020). 

Brisdelle treats the symptoms associated with menopause, including hot flashes and night sweats (NAMI, 2020).

Paroxetine can also be prescribed for other uses or what’s called “off-label.” The U.S. Food and Drug Administration (FDA) approves medications for specific uses. Off-label means using an FDA-approved drug for an unapproved use to treat other conditions—a standard practice when a healthcare provider deems a medication to be the right treatment for a patient (FDA, nd).

Some off-label uses for paroxetine include (Shrestha, 2021):

• OCD and social anxiety disorder in children and teens 

• Premature ejaculation

• Body dysmorphic disorder

• Postpartum depression

• Separation anxiety

• Dysthymia (mild and long-lasting depression)

• Itching due to cancer 

• Irritable bowel syndrome (NAMI, 2020)

• Stuttering (Medscape, nd)

Paroxetine is a selective serotonin reuptake inhibitor (SSRI) antidepressant. Serotonin is a neurotransmitter or chemical that affects the brain and helps you balance your mood. It treats depression and other mental conditions by keeping the amount of serotonin already there around for a more extended period, increasing serotonin’s mood-balancing effects (Shrestha, 2021). 

When you start taking paroxetine, you may show improvement in your energy levels or sleep quality within the first two weeks of taking it. Physical improvement is an excellent sign that paroxetine is working for you. It takes longer—between six to eight weeks—to lift your depressed mood (NAMI, 2020).

Paroxetine is not a short-term treatment. It does not cure your symptoms; rather, it controls them. That means it's essential to continue taking your medication and working with your healthcare team to see if it's right for you.

Like any medication, paroxetine has potential side effects.

Some of the common side effects that generally go away with time include (NAMI, 2020):

• Constipation

• Diarrhea

• Dizziness

• Dry mouth 

• Increased sweating

• Nausea and vomiting

• Weight gain or loss

• Yawning

• Feeling tired

• Nervous or restless

• Difficulty sleeping (insomnia)

• Inability to concentrate

Some other common adverse effects are more likely to stick around for as long as you take the medication. These include (NAMI, 2020):

• Erectile dysfunction

• Loss of libido

• Sexual dysfunction 

• High blood pressure

Speak to your healthcare provider about decreasing your dose or changing your medication if these symptoms persist and disturb your quality of life.

Serious side effects

Serious side effects are not common but can occur. If you experience any of these symptoms, call your healthcare provider or 911 immediately (GlaxoSmithKlein, 2021).

• Abnormal bleeding: nosebleeds that are hard to stop, coughing up or throwing up blood, bruising easily and often, blood in your stool

• Angle-closure glaucoma: symptoms of eye pain, vision changes, redness or swelling in or around the eye

• High blood pressure

• Mania: intense excitement or euphoria. This may be an activation of mania or hypomania in bipolar disorder.

• Hyponatremia or low sodium levels: headache, weakness, fainting, seizures

• Lung problems: pneumonia with chest pain, fever, cough, and shortness of breath

• Seizures

• Serotonin syndrome: When your levels of serotonin are too high, you can have shakiness, very high fever, diarrhea, rapid heartbeat, anxiety, muscle rigidity, muscle twitching, and seizures. This is a serious medical condition that requires immediate medical attention. If you have any of these symptoms, head to the nearest emergency room.

This medication has a black box warning from the FDA (its most serious warning) for its potential to cause suicidal thoughts and behaviors in people under 24 years old (FDA, 2012).

Some people may have an allergic reaction to paroxetine or any of the brand-name versions of paroxetine. Mild allergic reaction symptoms include hives, itchiness, and redness. A severe allergic reaction may include these life-threatening symptoms: swelling in your body, especially in your mouth, tongue, and throat, and trouble breathing. This is a medical emergency. Call 911 or head to the nearest emergency room if you experience these symptoms while taking paroxetine (GlaxoSmithKlein, 2021).

If your child is taking paroxetine, they may experience a decreased appetite and weight loss. Your child’s healthcare provider will be monitoring their health and growth while taking this medication. Speak with their pediatrician about the risks and benefits of starting your child on paroxetine (GlaxoSmithKlein, 2021).

This is not a complete list of all the side effects of paroxetine. Speak with your healthcare provider if you experience new or worsening symptoms. If you feel you need to stop taking paroxetine due to its side effects, speak with your healthcare provider first. Stopping paroxetine too quickly can cause additional symptoms so it’s important to wean off the medication slowly if need be. 

Your dose depends on any underlying medical issues, your mental health diagnosis, and how severe your condition is. 

The doses available include (Medscape, nd):

• Paroxetine, Paxil, and Pexeva immediate-release tablets come in doses of 10 mg, 20 mg, 30 mg, and 40 mg.

• Paroxetine and Paxil also come as a liquid suspension with 10 mg per 5 mL.

• Extended-release paroxetine and Paxil CR tablets come in 12.5 mg, 25 mg, and 37.5 mg doses.

• Brisdelle® comes in a 7.5 mg capsule. This medication contains a much lower dose of paroxetine than the other formulations. Do not use this medication to treat depression without speaking to your healthcare provider. 

Paroxetine is usually taken once a day with or without food. If you feel nauseated after taking it, take it after eating. You can take this medication in the morning or at night (Shrestha, 2021).

What happens if I miss a dose?

If you miss your dose of paroxetine, take it as soon as you remember. If it is close to the time of your next dose, skip that dose. Do not double your next dose. Do not take more or less than is prescribed to you. If you have questions about a missed dose, speak with your healthcare provider (GlaxoSmithKlein, 2021).

Paroxetine may interact with prescribed medications, over-the-counter and illicit drugs, supplements, and herbs. Some of these may increase the severity of the side effects or decrease the effectiveness of paroxetine. 

One of the more severe side effects is serotonin syndrome. When the neurotransmitter serotonin builds up in your body, it can cause agitation, anxiety, diarrhea, fever, hallucinations, very fast heartbeat, high or low blood pressure, vomiting, muscle rigidity, muscle twitching, and seizures. Call your healthcare provider immediately if you experience any of these symptoms. Call 911 or go to your nearest emergency room if your symptoms worsen (GlaxoSmithKlein, 2021).

Medications you should not take with paroxetine

The following medications can dangerously interact with paroxetine. Let your healthcare provider know if you are taking any of these or before starting them if you are already taking paroxetine (GlaxoSmithKlein, 2021): 

• Monoamine oxidase inhibitors (MAOIs) like isocarboxazid (Marplan), linezolid (Zyvox), methylene blue, phenelzine (Nardil), selegiline (Eldepryl, Emsam, Zelapar), or tranylcypromine (Parnate); or if you have stopped taking them within the past two weeks

• Antipsychotics like thioridazine or pimozide (Orap)

• Selective serotonin reuptake inhibitors (SSRIs), such as sertraline (Zoloft) and fluoxetine (Prozac)

• Serotonin-norepinephrine reuptake inhibitors (SNRIs) like duloxetine (Cymbalta) or venlafaxine (Effexor) 

• Tricyclic antidepressants like amitriptyline (Elavil) and desipramine (Norpramin)

• Lithium, a medication to treat bipolar disorder

• Migraine medications called triptans

• Prescription pain relievers tramadol and fentanyl

• Herbal supplement St. John's wort and nutritional supplement tryptophan may cause serotonin syndrome when taken with paroxetine

This is not a complete list of potential drug interactions. Be open and honest with your healthcare provider about any medications (prescription or over-the-counter), supplements, or illicit drugs or substances you are taking. That will help your healthcare provider make the safest recommendations for your treatment. 

Paroxetine carries a black box warning from the FDA that it may cause an increased risk of suicidal thoughts or behaviors in people under 24. 

Pregnant people should not take paroxetine. Paroxetine can severely affect the fetus or newborn babies when taken during pregnancy. If you become pregnant while taking paroxetine, call your healthcare provider immediately. If you plan on breastfeeding your baby, you may not be able to take paroxetine while doing so (NAMI, 2020). 

Paroxetine can cause mania or hypomania. Bipolar disorder also has depressive symptoms and is sometimes first misdiagnosed as depression alone. When a person with bipolar disorder takes paroxetine for depression, they may suddenly switch to mania with intense euphoria, pressured speech, racing thoughts, and irritable mood (GlaxoSmithKlein, 2021). 

If you are older than 65, speak with your healthcare provider if paroxetine is for you. Many older people take medications that interact with paroxetine.

Paroxetine, like other antidepressants, can cause sleepiness. Do not drive or use equipment that can harm you until you know how paroxetine affects you.

Paroxetine and alcohol interact with each other. Both have sedating qualities and can cause extreme drowsiness. Illicit drugs can decrease the effectiveness of paroxetine or increase any adverse effects of this medication. Avoid both alcohol and illicit drugs if possible while taking paroxetine (GlaxoSmithKlein, 2021). 

This is not a complete list of precautions with paroxetine. Please speak with your healthcare provider before starting this medication and take it only as prescribed.

Your healthcare provider is an essential partner with you in your overall health. Keep your appointments and let them know how you feel when taking paroxetine, especially when they adjust your dose. 

You may want to keep a list of all your prescribed and regularly used over-the-counter medications, as well as the vitamins and supplements you use. Refer to this list whenever you need to add another medication to prevent the risk of an adverse drug reaction.

Paroxetine may help you control the symptoms of your condition after several weeks but will not necessarily cure it. Continue to take paroxetine as directed by your healthcare provider. 

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Current version

July 21, 2021

Written by

Tobi Ash, MBA, RN, BSN

Fact checked by

Steve Silvestro, MD

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About the medical reviewer

Steve Silvestro, MD, Ro

Dr. Steve Silvestro is a board-certified pediatrician and Associate Director, Clinical Content & Education at Ro.