Paroxetine (Paxil) for PMS: does it work?

Paroxetine for PMS has solid trial support, but nearly all of it comes from women with the severe form, premenstrual dysphoric disorder (PMDD), not from typical premenstrual syndrome.

In trials where women met strict criteria for PMDD, daily paroxetine had a response rate of 85%, with the strongest effect on irritability (effect size 1.4) and a smaller one on low energy (effect size 0.5).

If your premenstrual symptoms are uncomfortable but don't disrupt your week, most guidelines suggest starting with other PMS treatments before an SSRI. If they're severe enough to affect your work, your relationships or how you show up every month, paroxetine has real evidence behind it, and the fuller trial picture is on our paroxetine for PMDD page.

Paroxetine has been tested in several randomized, placebo-controlled trials, almost all in women diagnosed with PMDD under DSM-IV criteria. Here's a summary of the main ones.

Across these trials, paroxetine works most reliably against irritability and mood swings, and the effect often shows up in the first treated cycle. Our PMS and PMDD research page covers how these trials are designed.

Paroxetine for premenstrual symptoms can be taken two ways, and trials show both work.

• Daily: one dose every day of the month, the same schedule used for depression.
• Luteal-phase only: starting around ovulation and stopping when your period begins, then restarting the next cycle.

Studied doses range from 10mg to 25mg a day, in either immediate-release or controlled-release (CR) form. In one trial, 20mg taken luteal-only cut irritability more than placebo, while 10mg didn't beat it, so dose matters.

Only a doctor can decide which schedule and dose fit you, based on how severe your symptoms are and how you've responded before. If you want to walk into that appointment with real data, tracking symptoms by cycle day on a DRSP chart makes the conversation faster.

Paroxetine often starts working faster for premenstrual symptoms than it does for ongoing depression. In one trial, irritability, mood swings and affect lability improved quickly enough that luteal-phase-only dosing worked almost as well as taking it daily.

Depressed mood and the broader physical-symptom scores measured in these trials tended to settle more gradually, closer to two or three treatment cycles in the larger trials. In an open trial of 14 women, depression ratings on a standard scale dropped from an average of 14.9 to 8.2 in the first treated cycle, and stayed around 7.8 by the third.

That quick response to irritability is part of why some doctors try the luteal-only schedule first. The drug doesn't need weeks to build up the way it does for depression.

Paroxetine's side effects are typical for an SSRI, though it tends to cause a bit more sedation, constipation, sexual difficulty and weight gain than some other SSRIs.

Common ones reported in trials:

• Nausea, especially in the first week (less with the CR form)
• Drowsiness or feeling slowed down
• Constipation
• Lower interest in sex or trouble reaching orgasm
• Weight gain with longer use
• Withdrawal-like symptoms if you stop suddenly

In the 2004 trial of 327 women, 9.5% of those on the 12.5mg dose and 13.5% on 25mg stopped the drug because of side effects, compared with 6.5% on placebo. Most people who stay on it tolerate it well enough to finish a trial of several cycles, but it's worth deciding with your doctor whether the trade-off fits you.

Paroxetine isn't right for everyone.

• You're pregnant or trying to become pregnant: it's classified as Pregnancy Category D, meaning there's evidence of risk to a developing fetus.
• You're under 18: it hasn't been studied or approved for premenstrual symptoms in that age group.
• You're already taking another serotonergic medication: combining them needs a doctor's input first.
• You've had a rough reaction to an SSRI before, like severe nausea or agitation that didn't settle.

None of this means living with symptoms that are wrecking your month. A doctor can weigh these risks against how much you're struggling, and a PMDD specialist can help if your regular doctor isn't sure where to start.

Medication tends to work better alongside a few other things.

• Cognitive behavioral therapy (CBT) has its own evidence for premenstrual mood symptoms and can help whether or not you're on an SSRI.
• Tracking your cycle for two months with daily ratings helps you and your doctor see what's actually tied to your luteal phase versus what isn't.
• Basic sleep, movement and cutting back on alcohol in the week before your period won't replace medication, but they lower the baseline you're starting from.

Niyora is a PMS and PMDD support app.

If you want somewhere to put the fight or the crying spell before you decide what to do with it, Niyora's Moon lets you write what happened, see it from another angle and calm down enough to draft a reply you can hold onto for 20 minutes.

It won't replace paroxetine or a diagnosis, but it can help on the night none of that is in reach.