PMS and PMDD
Premenstrual syndrome (PMS/PMDD) treatment in Ireland
Medically reviewed by Dr. Phil Boyle, MICGP, MRCGP · Last reviewed July 2026
PMS and PMDD are hormonal and endorphin-driven conditions that arise in the second half of the cycle. At NeoFertility, we identify what is driving symptoms and treat the underlying cause, most often with cycle balancing and Low Dose Naltrexone. In our clinical experience, they are very treatable.
What PMS and PMDD are
PMS is a recurring symptom cluster that appears before your period and clears when it starts.
The symptoms typically include bloating, breast tenderness, mood changes, irritability, carbohydrate cravings, and disturbed sleep. One or two days before your period falls within the range of normal. Four or more days consistently, cycle after cycle, that crosses into PMS.
PMDD, or premenstrual dysphoric disorder, is a mouthful, but it just means the severe end of the PMS spectrum. The same symptom cluster, at an intensity that interferes with your ability to function: work, parenting, relationships.
The second half of the cycle becomes a stretch of time women dread. Around 25% of women experience PMS. Around 5% have PMDD.
Bear in mind: what matters diagnostically is the cyclical nature. True PMS disappears with the onset of menstruation. If symptoms persist throughout the cycle, that points toward a different underlying condition and needs a different investigation.
What causes PMS and PMDD
Often, the core driver is low endorphins, resulting in symptoms during the luteal phase.
In our clinical experience, women with PMS consistently show lower levels of luteal phase progesterone, oestradiol, and beta-endorphin compared to women without PMS.
We call this presentation a clinical endorphin deficiency. It is the reason Low Dose Naltrexone is central to the treatment protocol.
How PMS is investigated at NeoFertility
A symptom diary alone is not enough.
We look at the full hormonal picture across the cycle. That means progesterone 7 days after ovulation, the timed blood test that tells us about the quality of ovulation.
We look at oestradiol at the same timepoint. And we look at the mucus pattern charted through ChartNeo.
The ChartNeo app lets you document symptoms and their severity against each cycle day. The result is a precise picture of where in the cycle the problem lies, jumping off the page. Fertility charting is useful here even if you are not trying to conceive.
The PMS treatment protocol
Treatment for PMS at NeoFertility follows a structured protocol.
The protocol follows a step-by-step order.
First, we look at diet. Avoiding dairy, gluten, and fast carbohydrates consistently reduces the symptom burden in the luteal phase. The mechanism is partly inflammatory and partly hormonal.
Second, we look at exercise. Twenty minutes a day, four times a week. Exercise produces its own endorphin surge, which is directly relevant to the clinical endorphin deficiency picture.
Third, we look at supplements. B vitamins and omega 3 have good evidence for reducing PMS symptoms and are part of the core protocol.
Low dose naltrexone for PMS and PMDD
The beauty of Low Dose Naltrexone is that it works with your body's own endorphin system.
Taken in a low nightly dose, LDN briefly blocks your endorphin receptors. The following day, your system rebounds with a surge of endorphins. Dr Bernard Bihari, who developed LDN therapy, described this rebound as a three-to-fourfold increase in beta-endorphin production.
The mechanism is similar but better than a good bout of exercise: you get a surge of endorphins and everything just feels better. For women with a clinical endorphin deficiency, particularly those with PMDD, the effects can be life-changing.
In our clinical experience, approximately 80% of women with PMS or PMDD respond to LDN. It is well tolerated. Over 95% of patients find the side effects acceptable.
In Boyle et al. 2025 (JRRM), 71% of all couples treated at NeoFertility receive LDN as part of their treatment plan.
In my view, in clinical practice, I would really suffer without having the ability to recommend Low Dose Naltrexone to my patients. That is how central it has become to the work we do.
LDN is off-label for PMS, but bear in mind, hormonal contraceptives are also used off-label for period pain, endometriosis, and PMS.
When PMS needs further investigation
Some women do not respond fully to the first steps.
In those cases, we look deeper. We look at progesterone support for the luteal phase, we look at adrenal function, and we look at thyroid dysfunction. Suboptimal thyroid or adrenal function can amplify PMS symptoms significantly, and sometimes it is the primary driver.
For a smaller number of women, sympathomimetic medication is the right next step. The point is we do not stop at the first answer. Treatment is a process over time, and we follow the clinical picture.
PMS and other reproductive health conditions
NeoFertility treats the full range of reproductive health conditions.
NeoFertility treats PMOS/PCOS, endometriosis, hormonal dysfunction, recurrent miscarriage, and postnatal depression, as well as PMS and PMDD. These conditions frequently overlap.
A woman presenting with severe PMS may also have underlying thyroid dysfunction or adrenal issues relevant to her broader cycle health. NeoFertility investigates the whole picture.
There is a close relationship between postnatal depression and hormonal disruption after delivery. For more, see the postnatal depression page.
What to expect from PMS treatment
You do not need a GP referral to come to NeoFertility.
Your first appointment covers your symptom history, your cycle history, and a plan for initial hormone tests timed to your next cycle.
Medical treatment, including LDN where indicated, typically begins within your first or second cycle. We remain your treating clinicians throughout.
See how the full NeoFertility treatment plan works
Frequently asked questions
What is the difference between PMS and PMDD?
PMS, or premenstrual syndrome, is a cluster of physical and emotional symptoms that appear in the days before your period and disappear when it starts.
One or two days of symptoms before your period falls within the range of normal. Four or more days consistently, cycle after cycle, crosses into PMS.
PMDD, premenstrual dysphoric disorder, is the severe end of the spectrum. The same symptom cluster, but at a level that interferes with your ability to function at home or at work.
Mood changes, severe irritability, fatigue, and physical symptoms can make the second half of the cycle very difficult. Both are treatable. PMDD in particular tends to respond remarkably well to treatment.
What causes PMS and PMDD?
The core driver is a drop in endorphin levels during the luteal phase of the cycle. That is the two weeks between ovulation and your period.
In our clinical experience, women with PMS show decreased luteal phase progesterone, oestradiol, and beta-endorphin levels compared to women without PMS. We see this pattern consistently.
The hormonal environment after ovulation matters too. Suboptimal progesterone can amplify the symptom burden. So when we investigate PMS, we look at the endorphin picture and the hormonal picture together.
How does Low Dose Naltrexone help with PMS?
Low Dose Naltrexone, or LDN, is an off-label prescription treatment that boosts your body's own endorphin production.
It works like this: LDN briefly blocks your endorphin receptors at night, then triggers a rebound surge the following day. Dr Bernard Bihari, who developed LDN therapy, described this as a three-to-fourfold increase in beta-endorphin levels.
The effect is similar to a good bout of exercise: you get a surge of endorphins and everything just feels better.
In our clinical experience, approximately 80% of women with PMS or PMDD respond to LDN. Common side effects include vivid dreams and some nausea in the first week or two. Over 95% of patients find these acceptable.
In our 2025 published data (Boyle et al., JRRM), 71% of all couples we treat receive LDN as part of their plan.
LDN is off-label for PMS, but bear in mind, hormonal contraceptives are also used off-label for period pain, endometriosis, and PMS. That is nothing unusual.
Does treating PMS help with fertility?
Often, yes. PMS symptoms are frequently a signal that the luteal phase hormonal environment is not optimal.
Low progesterone, poor quality of ovulation, low endorphin levels. These are the same factors that affect the uterine environment in early pregnancy.
So when we treat PMS as part of a restorative cycle workup, we are often improving the conditions for conception and early pregnancy at the same time. Treating PMS is not a side task. It is part of restoring the cycle to full health.
Can I come to NeoFertility for PMS if I am not trying to conceive?
Yes. We treat the full range of reproductive health conditions.
NeoFertility is not a fertility clinic in the narrow sense. We treat PMOS/PCOS, endometriosis, hormonal dysfunction, postnatal depression, and premenstrual syndrome in women who have no immediate interest in pregnancy.
If your cycle is causing you significant symptoms, that is worth investigating and treating. You do not need to be trying for a baby to come and see us. You can self-refer directly, without a GP referral.
