Low-dose naltrexone for PMDD: does it work?

Low-dose naltrexone (LDN) is not a proven PMDD treatment. If you're new to the diagnosis itself, start with PMDD, explained before weighing any specific option.

Nobody has tested naltrexone against PMDD as doctors define it today. Here's what we actually know:

• The only trial dosed naltrexone for premenstrual syndrome (PMS), not PMDD, back in 1988, years before PMDD became a formal diagnosis.
• That trial found a real improvement in symptom scores.
• It has never been repeated.

One small, old trial in a broader condition isn't the same thing as evidence for PMDD specifically, and no one has repeated it since. That gap matters if you're deciding whether to ask a doctor about it.

The single trial behind naltrexone for premenstrual symptoms is a double-blind, placebo-controlled crossover study from 1988, published in Obstetrics and Gynecology [1]. Twenty women with PMS took either naltrexone or placebo from day 9 to day 18 across three consecutive cycles, then switched.

Sixteen women completed it. On naltrexone, their symptom questionnaire scores dropped by an average of 28 points compared with placebo, a result unlikely to be chance (P = .016).

Most women did better on naltrexone than placebo, which is why this trial still gets cited. But it tested general PMS symptoms, not the five-symptom, mood-anchored criteria used for PMDD today, and it has never been repeated. For the PMS version of this question, see low-dose naltrexone for PMS.

We don't know, honestly. The 1988 trial gave naltrexone or placebo from day 9 to day 18 of each cycle, then measured symptoms with a questionnaire on day 25 of each of three cycles [1]. It didn't track how quickly relief started within that window.

That makes timing hard to predict for PMDD. The 1988 trial tracked symptoms over three cycles, but no study has established how long it takes to know whether naltrexone is helping. A doctor would set that timeline with you.

No published PMDD trial specifies the naltrexone dose used, either; the 1988 study didn't report one. For how low-dose naltrexone is typically dosed for other conditions, see LDN dosage, though a doctor would set the actual dose here.

Compare that with SSRIs taken only in the luteal phase, which can ease mood symptoms within days of starting each cycle for women who respond. Naltrexone hasn't been timed that precisely in any published PMDD research.

The 1988 trial described naltrexone as generally well tolerated, with most side effects mild [1]. Women taking naltrexone reported:

• Nausea
• Decreased appetite
• Dizziness

The researchers rated overall acceptability as good, but with only 16 women followed for three cycles, rarer or longer-term effects wouldn't have shown up. That short list doesn't rule out other reactions a longer, larger trial might find.

Naltrexone used for other conditions can also raise liver enzymes at some doses, which is one reason doctors check liver function before prescribing it. If side effects feel worse than the days you're trying to treat, tell your doctor rather than pushing through.

Naltrexone blocks opioid receptors, so it isn't safe to combine with opioid pain medicine. If you take anything containing codeine, tramadol or a stronger opioid, that combination needs a doctor's review first, since naltrexone can block the pain relief or bring on withdrawal.

People with liver disease are usually assessed carefully before starting any opioid antagonist. Naltrexone's safety in pregnancy hasn't been established, so it's generally avoided there without specialist guidance.

No major PMDD guideline, including ACOG or RCOG, lists naltrexone as a recommended treatment. The options with stronger evidence are covered in PMDD treatment: what actually helps.

A PMDD specialist can help you weigh an unproven option like naltrexone against what's already recommended for your symptoms.

Naltrexone, if a doctor prescribes it, doesn't have to stand alone. The treatments with the clearest evidence for PMDD work through different routes, and some people combine approaches under medical guidance.

• SSRIs, taken daily or only in the luteal phase, for mood symptoms
• Certain hormonal contraceptives, to steady the hormone swings that trigger symptoms
• Cognitive behavioral therapy (CBT), for the thought patterns around the days before your period

Tracking matters whatever you try. A DRSP chart kept for two cycles shows your doctor exactly when your symptoms are strongest and whether a treatment is changing that pattern. A doctor decides what to try first and whether naltrexone has a place alongside it.

While you wait to see whether any treatment helps, the days before your period still need something to do right now. A rough evening doesn't mean a medicine failed. It means the days before your period are still happening while your body adjusts.

Niyora is a PMS and PMDD support app. If you want somewhere to put a fight before you answer it, Niyora's Moon lets you write what happened, see it from another angle and draft a reply you can hold for 20 minutes.