Premenstrual syndrome
Exam Tips
- Diagnosis is prospective: ask for 2-3 cycles of daily ratings (DRSP) rather than relying on retrospective recall.
- Key discriminator is timing plus impairment: luteal worsening, relief with menstruation, and a symptom-free interval.
- If symptoms are non-cyclical, prioritise alternative diagnoses (depression, thyroid disease, anaemia, IBS, endometriosis).
- Always assess risk: severe PMS/PMDD can be associated with suicidality; this changes urgency and referral pathway.
- In refractory cases, symptom resolution on GnRH suppression supports a true ovarian-cycle-mediated disorder. See Figure: DRSP-style cycle chart interpretation (teaching handout).
Definition
Premenstrual syndrome (PMS) is a cyclical disorder in ovulatory menstrual cycles, where psychological, physical and behavioural symptoms reliably appear in the luteal phase and settle at or soon after menstruation. The diagnosis depends more on symptom timing and functional impact than symptom type, and requires clinically significant impairment (for example at work, school, or in relationships) rather than mild physiological premenstrual symptoms.
Pathophysiology
PMS appears to arise from abnormal central sensitivity to normal ovarian hormonal fluctuations rather than absolute hormone excess/deficiency. Key mechanisms include altered serotonergic signalling (supported by SSRI efficacy), altered GABA-A modulation by progesterone metabolite allopregnanolone, and likely multifactorial contributors such as genetic susceptibility, stress-related autonomic amplification, and immune-inflammatory effects. Ovulation is usually required, explaining absence before puberty and after menopause, and improvement during pregnancy. See Figure: luteal-phase hormone fluctuation versus symptom curve (teaching menstrual-cycle diagram).
Risk Factors
- Ovulatory menstrual cycles (strongest risk factor)
- Family history of PMS/PMDD (including twin association)
- Current or past mood disorder
- Cigarette smoking
- Alcohol use (higher risk with heavy intake)
- Psychological trauma/sexual abuse history
- Stress
- Weight gain/high BMI
Clinical Features
Symptoms
- Cyclical mood swings, irritability, anxiety, low mood, feeling out of control
- Poor concentration, reduced cognitive efficiency, food cravings, altered libido
- Bloating, breast tenderness, headache, backache, acne, GI upset, perceived weight gain
- Symptoms peak in luteal phase and improve with onset of bleeding, followed by a symptom-free interval
Signs
- Often normal examination between episodes
- Possible breast tenderness on palpation
- Abdominal bloating/distension without other red-flag findings
- Mild fluid-related weight fluctuation
- If pelvic pain/swelling is present, exam may suggest an alternative diagnosis and should prompt full pelvic/abdominal assessment
Investigations
Management
Lifestyle Modifications
- Explain diagnosis and cyclical nature; validate symptoms and agree shared plan
- Regular aerobic exercise, sleep optimisation, stress-reduction strategies (CBT/mindfulness where available)
- Reduce alcohol and smoking; moderate caffeine/salt if bloating prominent
- Structured symptom tracking to monitor response and distinguish PMS from persistent mood disorder
- Safety-net for self-harm/suicidal ideation and involve mental health services urgently if risk identified
Pharmacological Treatment
Selective serotonin reuptake inhibitors (first-line for moderate-severe PMS/PMDD features)
- Fluoxetine 20 mg orally once daily (continuous, or luteal-phase dosing from ovulation/day 14 to onset of menses)
- Sertraline 50 mg orally once daily, increase if needed (usual range 50-150 mg/day; some patients use luteal-phase dosing)
Rapid symptom benefit can occur in PMS. Counsel on nausea, insomnia, sexual dysfunction, discontinuation effects, and serotonin syndrome risk (especially with interacting serotonergic drugs). Monitor mood and suicidality, particularly in younger patients.
Combined hormonal contraception (symptom suppression in selected patients)
- Ethinylestradiol 30 micrograms/drospirenone 3 mg tablet once daily in a 21/7 or tailored continuous regimen
- Ethinylestradiol 20 micrograms/drospirenone 3 mg once daily (24/4 regimen where available)
Useful when contraception is also needed. Avoid if UKMEC contraindications apply (for example migraine with aura, current/history of VTE, smoking age >=35 years with heavy smoking, uncontrolled hypertension, estrogen-dependent cancer). Discuss VTE risk and warning symptoms.
Ovulation suppression with estrogen (specialist use)
- Estradiol transdermal patch 100 micrograms/24 hours changed twice weekly
- Estradiol gel 1.5 mg daily (dose adjusted to response)
If uterus present, add cyclical progestogen for endometrial protection (for example micronised progesterone 200 mg at night for 12 days/cycle). Monitor for estrogen-related risks; avoid in contraindicated patients (e. g, active thromboembolic disease, hormone-sensitive malignancy).
GnRH analogues (diagnostic/therapeutic in severe refractory disease, specialist care)
- Goserelin 3.6 mg subcutaneously every 28 days
- Leuprorelin 3.75 mg intramuscularly monthly
Induces medical menopause and may confirm diagnosis if symptoms remit. Limit duration without add-back because of bone loss and hypoestrogenic adverse effects; usually prescribe add-back HRT and monitor bone health.
Surgical / Interventional
- Hysterectomy with bilateral salpingo-oophorectomy in carefully selected severe refractory cases after specialist multidisciplinary assessment and usually after a successful GnRH trial
Complications
- Marked occupational/academic and interpersonal impairment
- Comorbid depression/anxiety and reduced quality of life
- Increased risk of suicidal behaviour in severe cases (especially PMDD spectrum)
- Possible increased risk of postnatal depression
Prognosis
Symptoms usually persist across reproductive years rather than resolving spontaneously before menopause, but many patients achieve good control with lifestyle and stepwise pharmacological treatment. Symptoms typically improve during pregnancy and cease after menopause if ovarian cycling stops.
Sources & References
🏥BMJ Best Practice(8)
✅NICE Guidelines(1)
- Premenstrual syndrome[overview]