Paxil dosage, forms, and strengths

Paxil, GlaxoSmithKline’s brand name for paroxetine hydrochloride, is a prescription drug approved by the U.S. Food and Drug Administration (FDA) to treat adults 18 years and older for the following:

• Major depressive disorder (MDD)

• Obsessive-compulsive disorder (OCD)

• Panic disorder

• Social anxiety disorder (SAD)

• Generalized anxiety disorder (GAD)

• Post-traumatic stress disorder (PTSD)

Paxil is also approved to treat adolescents for obsessive-compulsive disorder (ages seven and older) and social anxiety disorder (ages eight and older). Paxil CR, an extended-release formulation, is approved to treat premenstrual dysphoric disorder (PMDD) in women ages 18 and older.

Paxil is in a class of drugs called selective serotonin reuptake inhibitors (SSRIs), a drug class that also includes commonly prescribed antidepressants such as Prozac (fluoxetine), Zoloft (sertraline), Lexapro (generic name escitalopram), and Celexa (citalopram). 

Serotonin is a neurotransmitter, or chemical messenger, that carries signals between nerve cells, or neurons, in the brain. When the brain sends a message, serotonin is released from one neuron and then picked up and reabsorbed by a receptor on the receiving neuron. Paxil works by blocking the reabsorption, or reuptake, of serotonin at the receptor of the receiving neuron. This allows for more serotonin, thought to have a positive influence on mood, emotion, and sleep, to be available to improve the transmission of messages between neurons. SSRIs are called selective because their main effect is on serotonin and not on other neurotransmitters.

Paxil dosage forms and strengths

Paxil and generic paroxetine are currently available in the following dosage forms:

Paxil (paroxetine HCl immediate-release) dosage forms: 

• Tablets: 10 mg, 20 mg, 30 mg, 40 mg

• Liquid oral suspension: 10 mg per 5 mL

Paxil CR (paroxetine extended-release) dosage form: 

• Tablets: 12.5 mg, 25 mg, 37.5 mg

Generic versions of paroxetine are available in the following dosage forms:

• Capsule: 7.5 mg

• Tablets: 10 mg, 20 mg, 30 mg, 40 mg

• Extended-release tablets: 12.5 mg, 25 mg, 37.5 mg

Paxil dosage for adults

Regardless of the condition treated, Paxil immediate-release tablets are usually started at a dose of 20 mg a day and then may be increased by 10 mg daily every seven days until the maximum daily dose is reached. Older patients (age 65 and older) should begin with an initial dose of 10 mg daily and not exceed a maximum daily dose of 40 mg a day. 

When using Paxil CR or the extended-release generic form, the usual starting dose is 12.5-25 mg daily, increases should be made by 12.5 mg every seven days, and the maximum daily dose should be between 25-75 mg per day depending on the condition being treated. The daily dose for the extended-release form should not exceed 50 mg per day in seniors.

The following dosage charts provide more specific information.

Paxil dosage for PMDD

The recommended starting dosage of Paxil CR, or extended-release paroxetine, in women with PMDD is 12.5 mg per day. It may be taken either continuously, i.e., every day of the month, or intermittently starting 14 days prior to the onset of the period and continuing to the day the period begins. This intermittent dosing schedule is repeated with each new cycle. 

In women with inadequate response at 12.5 mg, the dosage may be increased by 12.5 mg to reach the maximum recommended dosage of 25 mg per day.

Paroxetine dosage for menopausal vasomotor symptoms

Paroxetine 7.5 mg capsules are available under the brand name Brisdelle for the treatment of moderate to severe vasomotor symptoms (hot flashes) associated with menopause. The recommended dosage is 7.5 mg once daily at bedtime.

Paxil dosage for children and adolescents

All SSRIs, including Paxil, carry a boxed warning (also called a black box warning) regarding the risk of increased suicidal thinking and behavior in some younger patients. Patients of all ages who are started on Paxil should be monitored for signs of suicidal thoughts and behaviors. 

The FDA has approved Paxil for use in children and adolescents for obsessive-compulsive disorder (ages seven and above) and social anxiety disorder (ages eight and above). Paxil for immediate release is also available as a liquid suspension for those who cannot swallow a pill.

Paxil dosage restrictions

Certain conditions will require modifications of the dosing of Paxil. Due to increased concentrations of Paxil in the blood, the recommended starting dose for people with severe renal or hepatic impairment is 10 mg daily and dosage should not exceed 40 mg per day.

Paxil dosage for pets

The FDA has not officially approved the use of Paxil in animals. The FDA does allow veterinarians to prescribe human medicines off-label, or for unapproved uses, for certain conditions in animals. For example, Paxil is used to treat aggression, anxiety, and obsessive-compulsive behaviors in dogs. In cats, Paxil has been used to treat aggression, urine marking, and other behavior problems.

In dogs, the usual dose of Paxil is 0.5 to 1mg per pound by mouth once daily. In cats, the usual dose is 0.25 to 0.75 mg per pound by mouth once daily.

How to take Paxil

Paxil should be taken once daily with or without food. It may take a month or more before you feel the full benefits, so continue taking the medicine even if it doesn’t seem to be helping your symptoms. 

• Take your medicine as directed. Your dose may need to be changed several times to find what works best for you. 

• Oral liquid, Tablet, Extended-release Tablet: These are usually taken in the morning.

• Brisdelle capsule: Take at bedtime.

• Paxil should come with a Medication Guide. Ask your pharmacist for a copy if you do not have one.

• Missed dose: Take a dose as soon as you remember. If it is almost time for your next dose, wait until then and take a regular dose. Do not take extra medicine to make up for a missed dose.

• Store the medicine in a closed container at room temperature, away from heat, moisture, and direct light.

• Oral liquid suspension: Measure the oral liquid medicine with a marked measuring spoon, oral syringe, or medicine cup. Shake the bottle well just before you measure each dose.

• Tablet or Extended-release tablet: Swallow whole. Do not crush, break, or chew it. Do not use an extended-release tablet that is cracked or chipped.

• You may need to take this medicine for a month or longer before you feel better. If you feel that the medicine is not working well, do not take more than the normal dose. Call your healthcare provider for instructions.

• Store the medicine in a closed container at room temperature, away from heat, moisture, and direct light.

Paxil dosage FAQs

Paxil vs. Paxil CR: What’s the difference?

The main difference between Paxil and Paxil CR is the way the body absorbs the active ingredient in the drug, paroxetine. Paxil CR, or the extended-release formulation, delays the release of Paxil until the tablet has passed through the stomach. The drug is then released into the bloodstream over a longer period of time (about four to five hours). In clinical studies, those on Paxil CR experienced significantly less nausea, a common adverse event of SSRIs, than those taking the immediate-release tablets in the first week of treatment.

How long does it take Paxil to work?

Some improvements in sleep, energy, or appetite may occur within the first one or two weeks of daily treatment with Paxil. Early improvement in these symptoms can be an important sign that the medication is working. Studies have generally shown that the full benefits of antidepressant therapy, particularly for depressed mood, may take as long as 8 to 12 weeks. This timeline is variable because different people react to medicines in different ways.

How long does Paxil stay in your system?

The half-life of Paxil is approximately 21 hours, which means that one-half of the active drug is gone from the body within 21 hours after stopping the medication. Based on this half-life, some amount of Paxil will be detectable for approximately five days. Compared to other SSRIs, Paxil has the shortest half-life.

What happens if I miss a dose of Paxil?

If you miss taking your Paxil at your regular time, take it as soon as you remember. If the missed dose occurs too close to the time to take your next dose, skip the missed dose. Do not take two doses close to the same time.

How long can you take Paxil?

Oftentimes, the use of an antidepressant such as Paxil is intended as a long-term treatment to prevent a recurrence of symptoms. Dosage adjustments can be made to keep the patient on the lowest effective dosage, and patients should be periodically reassessed to determine the need for continued treatment. Paxil, like other SSRIs, has not been shown to cause serious problems when taken over the long term.

How do I stop taking Paxil?

Although Paxil is not considered addictive, missing several doses in a row or stopping treatment abruptly may cause withdrawal-like symptoms. This is sometimes called discontinuation syndrome and may include the following symptoms:

• Irritability

• Nausea 

• Feeling dizzy 

• Vomiting 

• Nightmares 

• Headache

• Paresthesias (prickling, tingling sensation on the skin)

Patients should seek medical advice when discontinuing treatment and be monitored for these symptoms. A gradual reduction in the dose rather than abruptly stopping is recommended whenever possible. If intolerable symptoms occur following a decrease in the dose or upon discontinuation of treatment, then resuming the previously prescribed dose may be considered. The healthcare provider may continue decreasing the dose but at a more gradual rate.

Can you overdose on Paxil?

Since the introduction of Paxil in the 1990s, there have been hundreds of reported cases of overdoses with Paxil alone and in combination with other substances. Of these, 48 cases were fatal and 17 appeared to involve Paxil alone. Commonly reported adverse events associated with overdose include:

• Drowsiness

• Coma

• Nausea

• Tremor

• Tachycardia (rapid heartbeat)

• Confusion

• Vomiting

• Dizziness

No specific antidotes for Paxil are known. If an overdose is suspected you should contact your healthcare professional immediately.

What interacts with Paxil?

The following medicines are contraindicated and you should not take Paxil if you are also taking:

• A monoamine oxidase inhibitor (MAOI) or have stopped taking an MAOI in the last 14 days

• Zyvox (linezolid)

• Mellaril (thioridazine)

• Methylene blue

• Orap (pimozide)

Other drugs with the potential to cause drug-drug interactions with Paxil include:

• Lithium

• Non-steroidal anti-inflammatory drugs (NSAIDs) (e.g., ibuprofen or naproxen)

• Phenytoin

• Propafenone

• Risperidone

• Tamoxifen

• Tramadol

• Tricyclic antidepressants (e.g., amitriptyline or desipramine)

• Triptans (e.g., sumatriptan or zolmitriptan)

• Tryptophan

• Warfarin

• Phenelzine

• St. John’s wort

This is not a comprehensive list and other drugs may interact with Paxil including prescription and over-the-counter medicines, vitamins, and herbal products. Consult your healthcare professional regarding medicines to avoid while taking Paxil

What happens when you mix Paxil and alcohol?

Although Paxil has not been shown to increase the mental impairment caused by alcohol, you should avoid alcohol because it may worsen your condition and increase adverse effects (e.g., sedation).

What are the potential side effects of Paxil?

Dry mouth, constipation, and GI symptoms are some common side effects of Paxil. Uncommon but serious side effects of Paxil may include serotonin syndrome, anaphylaxis (severe allergic reaction), angle-closure glaucoma, and hyponatremia (low sodium levels in the blood). Other side effects are possible. Ask your healthcare provider for a full list of side effects and interactions.

Is it safe to take Paxil during pregnancy?

Paxil is associated with a small risk of birth defects and its use is discouraged, particularly in the third trimester, in pregnant women. Paxil is secreted in human breast milk and you should not breastfeed while taking this medication. A woman’s healthcare provider is the best source of information when managing antidepressant treatment while pregnant or breastfeeding.

Related resources for Paxil dosages:

• Paxil medication guide

• Paxil CR medication guide

• Paxil prescribing Information

• Paxil CR prescribing information

• Brisdelle prescribing information

• Paroxetine (Paxil)

• Paxil