Key takeaways

Paxil, an SSRI approved by the FDA to treat various psychological disorders, works by increasing serotonin levels in the brain.
Common side effects of Paxil include nausea, drowsiness, insomnia, headache, and sexual dysfunction. Nausea typically improves within the first few weeks of treatment.
Serious side effects of Paxil can include worsening depression, suicidal thoughts, serotonin syndrome, low sodium levels, bleeding problems, and withdrawal symptoms upon discontinuation.
To avoid Paxil side effects, patients should discuss their health history with their healthcare provider, provide a complete list of current medications to prevent drug-drug interactions, avoid alcohol, and follow their prescription directions closely.

Paxil, GlaxoSmithKline’s brand name for paroxetine hydrochloride, is a prescription antidepressant approved by the U.S. Food and Drug Administration (FDA) to treat major depressive disorder, obsessive-compulsive disorder (OCD), generalized anxiety disorders, post-traumatic stress disorder, and premenstrual dysphoric disorder. Paroxetine is also available under the brand name Brisdelle for the treatment of moderate to severe vasomotor symptoms (hot flashes) associated with menopause.

Paxil is a member of a class of drugs called selective serotonin reuptake inhibitors (SSRIs) that work by increasing the levels of serotonin in the brain which is thought to have a positive influence on mood, emotion, and sleep.

As with any medication, it is important to be aware of adverse effects and drug-drug interactions before beginning therapy. The following information highlights potential Paxil side effects and how to avoid them.

Common side effects of Paxil

The most common side effects of Paxil include:

Nausea
Drowsiness
Insomnia
Asthenia (abnormal weakness or lack of energy)
Headache
Dry mouth
Constipation
Dizziness
Sweating
Sexual problems
Diarrhea
Tremor
Loss of appetite
Nervousness
Anxiety
Indigestion
Agitation
Visual disturbances
Tingling or pricking sensation in extremities
Abdominal pain
Rapid or irregular heartbeat

Nausea

Nausea is one of the most commonly observed adverse events associated with the use of Paxil. Paxil nausea often improves over the first week or two of therapy. Paxil CR, the extended-release formulation, delays the release of Paxil until the tablet has passed through the stomach and has been found to cause significantly less nausea than the immediate-release tablets.

Weight changes

Although both weight gain and weight loss have been reported by patients in Paxil clinical studies, weight gain was more commonly associated with its use. In a six-month comparative study of Paxil (paroxetine), Zoloft (sertraline), and Prozac (fluoxetine), significant weight gain (7% or greater increase in weight) was reported in 25.5% of Paxil users compared to 4.2% on Zoloft and 6.8% on Prozac.

Decreased appetite and weight loss have been reported in children and adolescents taking SSRIs, including Paxil. When beginning Paxil therapy, children and adolescents should have their weight and growth regularly monitored.

Sexual side effects

Although SSRIs as a drug class are known to cause sexual side effects, Paxil is associated with having the greatest risk for causing sexual dysfunction. It is not clearly understood how Paxil affects sexual function, but it is believed to be related to the increased level of serotonin. In clinical trials involving more than 3,200 patients, incidences of sexual adverse events were reported as follows:

Ejaculatory disturbance: 13%-28% of male trial patients
Impotence: 2%-9% of male trial patients
Decreased libido: 6%-15% of male trial patients; 0%-9% of female trial patients
Orgasmic disturbance: 2%-9% of female trial patients

Serious side effects of Paxil

The following list includes rare but serious, side effects of Paxil:

Worsening of depression
Mania or hypomania episodes
Serotonin syndrome
Bleeding problems
Anaphylaxis (severe allergic reaction)
Stevens-Johnson syndrome
Angle-closure glaucoma
Seizures
Hyponatremia (low sodium levels in the blood)
Vasculitis (inflammation of the blood vessels)
Pulmonary fibrosis (scarring of lung tissue)
Priapism (persistent and painful erection)
Extrapyramidal symptoms (drug-induced movement disorders)
Withdrawal symptoms

Suicidal thoughts

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 the following signs of suicidal thoughts and behaviors:

Attempts to commit suicide
Acting on dangerous impulses
Acting aggressive or violent
Thoughts about suicide or dying
New or worse depression
New or worse anxiety or panic attacks
Feeling agitated, restless, angry, or irritable
Trouble sleeping
An increase in activity or talking more than what is normal for you
Other unusual changes in behavior or mood

Serotonin syndrome

Serotonin syndrome is a serious and potentially life-threatening condition in which there is too much serotonin in the body. Paxil works by increasing the levels of serotonin which may lead to excess levels, especially when taken with other drugs that increase serotonin such as other SSRIs, triptans, tricyclic antidepressants, fentanyl, lithium, tramadol, tryptophan, buspirone, dextromethorphan, amphetamines, St. John’s Wort, and monoamine oxidase inhibitors (MAOIs).

Symptoms of serotonin syndrome may include:

Changes in mental health such as agitation, hallucinations, coma
Coordination problems
Muscle twitching
Racing heartbeat
High or low blood pressure
Sweating
Fever
Nausea, vomiting, or diarrhea
Muscle rigidity

Emergency medical care may be needed if any of these symptoms occur.

Low sodium blood levels

Low sodium blood levels, also known as hyponatremia, are a potential side effect of all SSRIs, including Paxil. Symptoms of low sodium levels may include:

Headache
Difficulty concentrating
Memory impairment
Confusion
Weakness
Unsteadiness

Bleeding problems

SSRIs, including Paxil, increase the risk of bleeding events. Use caution when also taking aspirin, nonsteroidal anti-inflammatory drugs (NSAIDS) such as ibuprofen or naproxen, warfarin, and other anticoagulants. There have been reported interactions between the use of these drugs and SSRIs causing gastrointestinal (GI) bleeding, bruising, nosebleeds, and even life-threatening hemorrhages.

Withdrawal symptoms

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 be monitored for these symptoms when discontinuing treatment. 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.

How long do side effects last?

Most common side effects related to Paxil, such as nausea, headache, and dizziness, tend to go away within two to four weeks as the body adjusts to the medicine. Some adverse effects, such as sexual problems, may persist. If beginning treatment with Paxil you should be monitored for worsening of depression, suicidal thoughts, or unusual changes in behavior.

Paxil contraindications & warnings

Contraindications

You should not take Paxil if you have a known allergy to any of its active or inactive ingredients. 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
Methylene blue
Zyvox (linezolid)
Mellaril (thioridazine)
Orap (pimozide)

Restrictions

Children and adolescents

Antidepressant medications, including Paxil, showed an increased risk of suicidal thinking and behavior in children, adolescents, and young adults. After initiating therapy with Paxil anyone younger than 25 years of age should be closely monitored for clinical worsening and suicidal or unusual behavior.

Children and adolescents are susceptible to changes in appetite or weight and should have their height and weight monitored during treatment.

Seniors

Because Paxil clinical studies showed a decreased clearance of the drug in older patients, they may be at greater risk for developing low sodium levels, or hyponatremia. This may be prevented by changing to a lower dose or less frequent dosing in patients older than 65.

Pregnancy and breastfeeding

Paxil is associated with an increased 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 it is not recommended to breastfeed while taking this medication. A woman’s healthcare provider is the best source of information when managing antidepressant treatment while pregnant or breastfeeding.

Overdose

Between the introduction of Paxil in the United States in 1992 through 1999, 342 incidences of deliberate or accidental overdose (dosage more than 70 mg per day) were reported. Of those, 48 cases were fatal and 17 appeared to involve Paxil alone. Of the 145 non-fatal cases reported with a known outcome, most patients recovered without permanent harm

Commonly reported adverse reactions associated with Paxil 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.

Paxil interactions

The following medicines have the potential to cause drug-drug interactions when taken at the same time as Paxil:

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 for professional medical advice regarding medicines to avoid while taking Paxil

How to avoid Paxil side effects

1. Talk to your healthcare professional about your health history

Before starting olanzapine, tell your healthcare professional if you have:

Plans to become pregnant, are pregnant, or are breastfeeding
Liver or kidney problems
Heart defects or disease
Seizures or convulsions or a history of seizures
Bipolar disorder or mania
Low sodium levels in your blood
A history of a stroke
High blood pressure (hypertension)
Bleeding problems or a history of bleeding problems
Glaucoma (high pressure in the eye)

2. Give your providers a full list of medications you’re taking

You should always tell your healthcare provider and pharmacist about which medications you’re currently taking. The following medicines or supplements may interfere with Paxil or cause side effects of paroxetine:

Triptans used to treat migraine headache
Other antidepressants (SSRIs, SNRIs, tricyclics, or lithium) or antipsychotics
Drugs that affect serotonin, such as lithium, tramadol, tryptophan, St. John’s wort
Drugs used to treat irregular heartbeats, schizophrenia, HIV infection, or epilepsy
Drugs that affect the blood, such as warfarin, aspirin, and ibuprofen
Atomoxetine
Cimetidine
Fentanyl
Metoprolol
Pimozide
Procyclidine
Tamoxifen

3. Avoid drinking 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).

4. Take Paxil as directed

Follow the directions on your prescription label and read all medication guides or instruction sheets.
Take Paxil exactly as prescribed; your healthcare provider may need to change the dose of Paxil until it is the right dose for you.
Paxil may be taken with or without food.
If you are taking Paxil Oral Suspension, shake the suspension well before use.
If you miss a dose of Paxil, take the missed dose as soon as you remember. If it is almost time for the next dose, skip the missed dose and take your next dose at the regular time. Do not take two doses of Paxil at the same time.
If you take too much Paxil, call your healthcare provider or poison control center right away, or get emergency medical attention.
Do not stop taking Paxil suddenly without talking to your doctor (unless you have symptoms of a severe allergic reaction); if you need to stop taking Paxil, your healthcare provider can tell you how to safely stop taking it.