Paroxetine (Paxil): What it is, How it Works, Uses & More

Kristin Hall

Medically reviewed by Kristin Hall, FNP

Written by Our Editorial Team

Last updated 7/19/2020

Paroxetine, commonly sold as Paxil®, is a prescription medication that’s used to treat depression, several anxiety disorders and other conditions including obsessive-compulsive disorder (OCD) and posttraumatic stress disorder (PTSD).

Paroxetine is a type of antidepressant referred to as a selective serotonin reuptake inhibitor, or SSRI. It works by increasing the level of neurotransmitters responsible for managing your mood and mental wellbeing in your brain and body.

If you’ve been diagnosed with depression, an anxiety disorder, or another condition that can be treated with SSRIs, your healthcare provider may recommend paroxetine.

As a modern antidepressant, paroxetine can help to improve mood and improve recovery from depression. Although it can cause side effects, it’s less likely to cause serious side effects than many older antidepressants. 

Below, we’ve explained what paroxetine is and how it works as a treatment for depression and other conditions. We’ve also looked at the potential side effects of paroxetine, drug interactions and other information that you should be aware of before using this medication.

What is Paroxetine (Paxil)?

Paroxetine is an antidepressant. It belongs to a class of medications called SSRIs. 

The most common use for paroxetine is as a treatment for depression. However, it’s also used to treat a range of mental health conditions, from anxiety and panic disorders to posttraumatic stress disorder and obsessive-compulsive disorder.

Under the brand name Brisdelle®, paroxetine is prescribed to treat certain symptoms of menopause, such as hot flashes. It’s also prescribed as Paxil CR® as a treatment for premenstrual dysphoric disorder — a severe form of premenstrual syndrome that affects up to eight percent of women. 

Paroxetine was approved by the FDA in 1992, making it a relatively new antidepressant. It’s an incredibly widely-used medication, with over 10 million prescriptions in the United States annually. 

As an SSRI, paroxetine is considered safer and less likely to cause side effects than the older antidepressants widely prescribed in the 20th century, such as tricyclic antidepressants (TCAs) and monoamine oxidase inhibitors (MAOIs).

You may have seen paroxetine sold under the brand name Paxil. Today, it’s widely available as a generic medication under a variety of brand names.

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How Paroxetine Works

As an SSRI, paroxetine works by changing the way your brain deals with important chemicals called neurotransmitters. More specifically, paroxetine prevents your brain from reabsorbing a neurotransmitter called serotonin. 

Neurotransmitters are a type of chemical messenger used by your brain and body to transport signals between neurons.

Your body uses serotonin to manage a diverse range of biological processes, from memorizing information and healing damaged tissue to regulating your appetite.

Serotonin is occasionally referred to as the “happy chemical.” This is because serotonin is the main neurotransmitter responsible for managing your general mood and level of happiness. 

People with depression, as well as certain anxiety disorders, often have low levels of serotonin. By preventing the reuptake of serotonin, paroxetine and other SSRIs increase the total amount of serotonin circulating in the brain.

This increase in serotonin can help improve your mood and treat many of the symptoms of depression and anxiety. 

Paroxetine Dosages

Paroxetine is prescribed at a range of dosages to treat depression, anxiety disorders and other conditions. 

For depression, the typical starting dose of paroxetine is 20mg per day. Based on your response to paroxetine symptoms, your healthcare provider may adjust your paroxetine dosage to a maximum of 50mg per day.

For obsessive-compulsive disorder, panic disorder, social anxiety disorder and other conditions, paroxetine is typically prescribed at a starting dosage of 20mg per day and a maximum dosage of 50mg 60mg per day, depending on the condition. 

For premenstrual dysphoric disorder, an extended-release version of paroxetine is prescribed at a typical starting dosage of 12.5mg per day, which may be adjusted up to a maximum dosage of 25mg per day. 

If you’re prescribed paroxetine to treat an anxiety disorder, depression, premenstrual dysphoric syndrome or any other condition, closely follow the dosage instructions provided by your healthcare provider and only use the medication as directed. 

Paroxetine Side Effects and Interactions

Paroxetine may cause a range of side effects. As with other antidepressants, most side effects from paroxetine are mild and transient. However, there are also severe less common, potentially more severe side effects that you should be aware of if you’re prescribed this medication.

Common side effects of paroxetine include:

  • Headache

  • Asthenia (weakness and/or lack of energy)

  • Vasodilation

  • Palpitation

  • Sweating

  • Rash

  • Nausea

  • Dry mouth

  • Constipation

  • Diarrhea

  • Decreased appetite

  • Flatulence

  • Oropharynx disorder (difficulty swallowing)

  • Dyspepsia (indigestion)

  • Myopathy

  • Myalgia

  • Myasthenia

  • Somnolence (drowsiness)

  • Dizziness

  • Insomnia

  • Tremor

  • Nervousness

  • Anxiety

  • Paresthesia (abnormal sensation of the skin)

  • Reduced libido

  • Drugged feeling

  • Confusion

  • Yawning

  • Blurred vision

  • Changes in taste

  • Changes in urinary frequency

  • Urination disorder

The most common side effects experienced by paroxetine users can differ slightly based on the condition the medication is prescribed to treat. 

For depression, the most common side effects reported in clinical trials are asthenia (weakness and/or lack of energy), sweating, nausea, reduced appetite, somnolence (drowsiness), tremor, sweating and certain sex-specific sexual side effects. 

In women, paroxetine is associated with a slight increase in sexual side effects, such as difficulty reaching or inability to reach orgasm (referred to as “anorgasmia” in documentation of paroxetine). This side effect occurred in approximately two percent of women given paroxetine in clinical trials. 

We have an article on the risks of using Paxil and alcohol if you'd like to learn more.

FDA “Black Box” Warning: Suicidal Thoughts and/or Behavior

Antidepressants, including paroxetine, are sold with a “black box” warning from the FDA listing a range of potentially serious side effects. 

These side effects include an increased risk of suicidal thoughts and/or behavior in children and young adults prescribed antidepressants. This risk is often at its highest during the first months of treatment. 

If you’re prescribed any type of antidepressant medication that carries this warning, contact your healthcare provider or healthcare professional as soon as possible if you experience any change in behavior, unusual thought patterns, feelings or thoughts about suicide. 

Interactions Between Paroxetine and Other Medications

Paroxetine can interact with other medications, including over-the-counter medications, herbal treatments, health supplements and other products. Some other medications may increase the amount of paroxetine in your bloodstream, causing potentially serious side effects.

You should not use paroxetine with other antidepressants, or if you have recently used certain types of antidepressant medication. 

If you have taken any monoamine oxidase inhibitors (MAOIs) in the last 14 days, you must not use paroxetine. MAOIs can interact severely with paroxetine, potentially leading to a dangerous condition called serotonin syndrome.

Common MAOI medications include phenelzine, isocarboxazid, tranylcypromine, selegiline and several others. If you’ve recently used an MAOI medication, inform your healthcare provider so that you can allow a safe amount of time to pass before beginning treatment with paroxetine. 

Other common antidepressants, including TCAs and other SSRIs, can also interact with paroxetine and increase your risk of experiencing side effects. 

You should also not use paroxetine with medications such as thioridazine, pimozide, the amino acid tryptophan, linezolid or methylene blue injection. All of these substances have a significant risk of causing dangerous side effects when used with paroxetine. 

Paroxetine can also interact with other medications, such as NSAIDs, drugs with serotonergic properties such as tramadol and fentanyl, antiarrhythmics, cimetidine, theophylline, quinidine, risperidone, amphetamines, lithium and other-the-counter products such as St. John’s wort. 

Finally, many other medications may make paroxetine less effective in the body. To avoid any serious or minor interactions, inform your healthcare provider about all medications, supplements, vitamins and other health products you regularly use before discussing paroxetine. 

Paroxetine and Pregnancy

Paroxetine has a category D rating from the FDA. This means that scientific studies have shown that there is evidence of risk to the fetus when this medication is used during pregnancy, though the potential benefits may still warrant the use of this medication in certain circumstances.

If you’re prescribed paroxetine, it’s important that you use a safe, effective form of contraception to reduce your risk of becoming pregnant.

If you think that you could be pregnant, or if you’d like to become pregnant, talk to your healthcare provider if you’re currently prescribed paroxetine. Do not suddenly stop using paroxetine without talking to your healthcare provider, as this may increase your risk of experiencing withdrawal-related side effects. 

Research shows that paroxetine can pass into breast milk. If you’re currently breastfeeding or if you plan to breastfeed your child in the future and use paroxetine to treat depression, an anxiety disorder or another condition, it’s important that you talk to your healthcare provider. 

Learn More About Medications for Depression

A wide range of medications are used to treat depression, from modern SSRIs like paroxetine to older depression medications such as TCAs and MAOIs. 

If you’ve been diagnosed with depression, an anxiety disorder, obsessive-compulsive disorder, posttraumatic stress disorder, or one of several other conditions, your healthcare provider may recommend getting a prescription for paroxetine online.

In other cases, your healthcare provider may recommend a different medication. We also have many blogs comparing different antidepressants, such as Paxil vs Prozac.

Frequently Asked Questions About Paroxetine

What is Paroxetine (Paxil) Used For?

Paroxetine (Paxil) is typically prescribed to treat depression. It’s also prescribed for a range of anxiety disorders, including generalized anxiety disorder and social anxiety disorder. In some cases, paroxetine is also used to treat the following conditions:

  • Obsessive-compulsive disorder (OCD)

  • Posttraumatic stress disorder (PTSD)

  • Panic disorder

  • Premenstrual dysphoric disorder (PMDD)

  • Menopause symptoms, such as hot flashes

How Long Does Paroxetine (Paxil) Take to Work?

Paroxetine usually takes four to six weeks to start working fully. If you’re prescribed paroxetine to treat depression or an anxiety disorder, you may notice some improvements in your energy levels, appetite and sleep during the first two weeks of use. We also have a detailed guide on paxil's first week side effects.

It may take up to eight weeks for paroxetine to work fully to treat some depression symptoms, such as a depressed mood and/or lack of interest in certain activities.

If you don’t experience any improvements after using paroxetine for several weeks, don’t stop using the medication. Instead, contact your healthcare provider. Depending on your symptoms and general health, they may recommend adjusting your dosage of paroxetine. 

How and When Should You Take Paroxetine (Paxil)? 

Paroxetine should be taken one time per day in the morning. Taking paroxetine in the evening or at night may increase your risk of experiencing insomnia, which is a common side effect of this medication.

You can take paroxetine with food or on an empty stomach. Some paroxetine users note that taking this medication on an empty stomach can worsen nausea-related side effects. For this reason, you may want to take paroxetine with a small meal.

If you forget to take paroxetine and remember on the same day before going to bed, take the missed dose as soon as possible. If it’s already late at night or the next day, skip the missed dose and continue using the medication as normal.

If you accidentally take too much paroxetine and vomit, feel overly sleepy, develop an overly fast heart rate, begin to shake or experience a fever or seizures, call 911 for emergency help immediately. 

How Should You Stop Taking Paroxetine (Paxil)?

If you no longer want to use paroxetine, you shouldn’t stop taking this medication without first talking to your healthcare provider. Like many other antidepressants, paroxetine can cause withdrawal side effects — some of which are potentially serious — if it’s stopped suddenly.

Before stopping paroxetine, talk to your healthcare provider. Depending on your symptoms, general health and other factors, they may recommend adjusting your dosage, switching to a different medication or gradually tapering your dosage of paroxetine over time.

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Can Paroxetine (Paxil) Cause Weight Gain? 

Paroxetine is one of the SSRIs most closely associated with weight gain. In a study from 2000, researchers found that paroxetine caused significant weight gain in patients, while other SSRIs caused either a modest increase in weight or a small amount of weight loss. 

A scientific review of antidepressants and weight gain, which featured the above study, noted that paroxetine users were more likely than users of other SSRIS to gain a significant amount (more than seven percent of their bodyweight) of weight after starting treatment. 

In short, paroxetine may be more likely than other medications to cause weight gain. However, not all people prescribed paroxetine gain weight. 

If you’re concerned about your weight after starting paroxetine, talk to your healthcare provider. Depending on your general health, symptoms and other factors, they may recommend switching to another medication that’s less likely to cause weight gain. 

This article is for informational purposes only and does not constitute medical advice. The information contained herein is not a substitute for and should never be relied upon for professional medical advice. Always talk to your doctor about the risks and benefits of any treatment. Learn more about our editorial standards here.

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