Paroxetine (Paxil)

What paroxetine is

Paroxetine is a medication sold under brand names including Paxil. It works mainly on serotonin, one of the chemical messengers nerve cells use to communicate, and medicines that work this way are often called SSRIs (selective serotonin reuptake inhibitors). It is widely used and well studied.

What it treats

Your clinician might suggest paroxetine for one of these, among other possible off-label uses:

• Depression
• Anxiety, including panic, social anxiety, and ongoing worry
• Obsessive-compulsive disorder
• Post-traumatic stress disorder
• Premenstrual dysphoric disorder (PMDD)

Whether it is a good fit depends on several factors, including your history and what you are working on. As with everything in psychiatry, that is decided case by case.

Who should not take paroxetine. FDA labeling lists a few firm exclusions. Paroxetine is not taken together with, or within 14 days of, a group of medicines called MAOIs, because the combination can cause a dangerous reaction called serotonin syndrome; that group includes the antibiotic linezolid and methylene blue given into a vein. It is not taken with thioridazine or pimozide. It is not for anyone who has had a serious allergic reaction to paroxetine. Make sure your clinician has your full medication list, including anything started recently or stopped within the last two weeks.

How it works

Honestly, no one knows with complete certainty how paroxetine produces its benefit. What research suggests is that it helps keep more serotonin available in the spaces between nerve cells, and that this serotonin effect is central to how it helps. The biology is only part of the picture: how much a medication helps, and how it feels, is individual. Two people on the same medication can have very different experiences.

How to take it

There is no single right way to take paroxetine; it depends on you and your clinician. Some people start low and increase slowly, others do not, and the timing and the form (immediate-release tablet, controlled-release tablet, or liquid) vary. The plan you and your clinician make together is the one to follow, not a number you read online. A few general points apply broadly:

• Take it the way you and your clinician agreed. It can be taken with or without food, and taking it with food can help if it bothers your stomach.
• Paroxetine leaves the body relatively quickly, so try to take it consistently. Missing doses or stopping suddenly is more likely to cause uncomfortable discontinuation effects with this medicine than with some others in its family, which is exactly why a planned, gradual taper matters when the time comes.
• If you miss a dose, ask your clinician or pharmacist what to do rather than doubling up.
• Try not to stop on your own. Your clinician can taper it gently if and when that makes sense.
• If you are planning a pregnancy or could become pregnant, mention it, and tell your clinician right away if you become pregnant or think you might be, because that affects whether paroxetine is the right choice for you.

What to expect

This varies from person to person. Some effects can show up before the benefit does: possible side effects, if they happen, often appear in the first days, while any lift in mood or easing of anxiety usually takes longer, commonly a few weeks and sometimes more. That early stretch is common and tends to ease. If nothing has shifted after a fair trial, that is useful information, not a dead end, and there are other options. As always, this is case by case.

Side effects

Not everyone gets side effects, and many that do happen ease over the first weeks. The lists below are possibilities, not certainties.

Possible more common side effects:

• Nausea, or other stomach upset, especially early on
• Trouble sleeping, or feeling drowsy or tired
• Feeling nervous or restless, or a fine tremor
• Headache, dizziness, or weakness
• Dry mouth, yawning, or sweating more than usual
• Less appetite, or changes in sex drive or sexual function

If any of these stick around or bother you, they are worth raising. Send a non-urgent message through the patient portal or bring it up at your next visit; often a small change helps. Restlessness or anxiety that is new, worsening, or severe is a reason to contact your clinician promptly rather than wait.

Less common, but concerning side effects that could require emergency care:

• Signs of an allergic reaction. Call 911 right away for swelling of the face, lips, tongue, or throat, trouble breathing, or blistering skin. Contact your clinician promptly about a new rash or hives.
• Serotonin syndrome: agitation, confusion, a racing heart, fever, heavy sweating, or stiff or twitching muscles, sometimes after another medication is added
• Unusual bleeding or bruising
• A seizure
• Feeling abnormally high, wired, or irritable, with racing thoughts and far less need for sleep than usual
• Eye pain or redness, or changes in vision such as blurred sight or seeing rings around lights
• Sudden nausea, weakness, confusion, or unsteadiness, which can signal a low sodium level
• Any new or worsening thoughts of harming yourself, whether or not you think the medication is behind it

For any of these, use the help options at the top of this page: call 911 or go to the nearest emergency department for a medical emergency or severe reaction, or call or text 988 for a mental health crisis.

If serotonin syndrome or a seizure is the concern, tell the clinicians treating you everything you take, including this medication. They may decide to stop it.

Pregnancy and breastfeeding

If you are pregnant, thinking about it, or breastfeeding, this is worth going through together rather than settling from a page. What follows is what the research currently shows. Tell your clinician before changing anything, and do not stop suddenly on your own.

In pregnancy

Paroxetine carries a specific caution about early pregnancy, and the sources do not describe it the same way. FDA labeling says paroxetine taken in the first trimester is associated with a less than 2-fold increase in heart defects, based on pooled analyses, while noting that individual studies have been inconsistent. It also says that for people who plan to become pregnant or are in the first trimester, paroxetine should be started only after the other treatment options have been considered. MotherToBaby, a teratology information service, says some studies found a small increase in birth defects, especially heart defects, that others did not, and that if there is an increase it is expected to be small. For scale, about 1 in 100 babies is born with a heart defect, and about 3 in 100 with any birth defect, before any particular exposure is considered.

Some studies have suggested a slightly higher chance of miscarriage. Depression is itself associated with miscarriage, which makes the two hard to separate.

A few other findings come up often enough to name:

• Preterm birth. Some studies suggest a higher chance when the medication is taken throughout pregnancy. Depression is itself associated with this outcome, which makes the two hard to separate.
• A newborn lung condition. Some studies suggest that SSRIs taken in the second half of pregnancy might raise the chance of persistent pulmonary hypertension of the newborn, and others have not found this. It occurs in about 1 or 2 of every 1,000 births to begin with, and if SSRIs do raise it, the overall chance stays under 1 in 100.
• Bleeding after delivery. FDA labeling notes that SSRI use, particularly in the month before delivery, has been associated with a higher chance of postpartum hemorrhage. Worth making sure whoever delivers your baby knows what you are taking, well before the day.
• Later learning and behavior. It is not known whether paroxetine affects later behavior or learning. One study based on prescription records suggested a higher chance of autism with SSRIs including paroxetine, and another did not; records of filled prescriptions cannot show whether the medication was taken. One small study of babies exposed at least in the third trimester (46 exposed, 23 not) found no developmental differences at 2 and 8 months, and a follow-up of some of those children (22 exposed, 14 not) found no differences in behavior.

Symptoms in the newborn. Babies exposed late in pregnancy can have temporary symptoms soon after birth, which are usually mild and go away on their own. They can include jitteriness, stiff or floppy muscle tone, irritability, trembling, more crying than usual, changes in sleep, a bluish tinge to the skin, trouble feeding, trouble holding a steady temperature, and trouble breathing. Not every exposed baby has them, and some babies stay in a special care nursery for several days. FDA labeling adds that some newborns have needed a longer hospital stay, help with breathing, or tube feeding. The useful thing you can do is make sure the delivery team knows about the medication ahead of time, so someone is watching for it.

While breastfeeding

Paroxetine passes into breast milk in small amounts and has not been detected in the blood of most babies tested. LactMed, the National Institutes of Health lactation database, notes that most authoritative reviewers consider paroxetine one of the preferred antidepressants during breastfeeding. Infants followed for up to 5 years have not shown effects on development. Occasional mild side effects have been reported, especially in babies whose mothers took paroxetine late in pregnancy, and it is not clear how much the milk contributes.

FDA labeling notes reports of breastfed babies with agitation, irritability, poor feeding, or poor weight gain. If you notice any of these, or unusual sleepiness, call the pediatrician.

Separately, some people taking an SSRI have a harder time getting breastfeeding established, and it is not clear how much of that is the medication and how much is the condition being treated. It is a good reason to line up lactation support early rather than to assume it will not work.

If you are a man taking paroxetine

SSRIs can cause sexual side effects. FDA labeling says paroxetine may affect sperm quality, which may affect fertility, and that it is not known whether the effect reverses. A father's use of paroxetine is not expected to raise the chance of birth defects.

Registries

There is a national registry that follows pregnancy outcomes for people taking psychiatric medications, and you can enroll yourself rather than waiting to be asked. It is listed in the references at the bottom of this page.

When to reach out, and where

For routine questions, side effects that can wait, or how things are going, send your clinician a message through the patient portal. These are part of your ongoing care and are answered in the normal course of a few business days, so they are best for things that are not urgent.

If something feels urgent, you do not need to wait for a reply. The help options at the top of this page are the fastest way to get care: 911 or the nearest emergency department for a medical emergency or severe reaction, or 988 any time for a mental health crisis or thoughts of self-harm.

Questions to ask your clinician

• What are you hoping paroxetine will help with in my case?
• How and when will we know if it is working?
• Given that it can be harder to stop, how will we plan that part?
• What should I do if I notice side effects?
• If I am or might become pregnant, how does that change things?
• How will we handle stopping it, if and when we get there?