Premenstrual Syndrome: Symptoms, Causes, and Diagnosis

What Is Premenstrual Syndrome?

Premenstrual syndrome (PMS) is a cyclical collection of physical and emotional symptoms that emerge in the late luteal phase of the menstrual cycle (typically 1–2 weeks before menstruation) and resolve within a few days of the period starting. The keyword is cyclical: symptoms occur reliably each cycle, in the same luteal-phase window, and are absent or minimal in the follicular phase.

Studies suggest that up to 80–90% of reproductive-age women experience at least one premenstrual symptom. However, clinically significant PMS — meeting formal diagnostic criteria — affects approximately 20–30% of women. Severe PMS and PMDD (Premenstrual Dysphoric Disorder) affect a smaller subset of 3–8%.

Symptoms of PMS

Emotional/Psychological Symptoms

• Irritability or anger — the most consistently reported symptom
• Mood swings or emotional sensitivity
• Anxiety or tension
• Low mood
• sadness
• or mild depression
• Reduced concentration and "brain fog"
• Social withdrawal or reduced desire for social interaction
• Insomnia or hypersomnia

Physical Symptoms

• Abdominal bloating and discomfort
• Breast tenderness or swelling
• Headaches (including migraines in susceptible women)
• Fatigue and low energy
• Joint or muscle aches
• Fluid retention and temporary weight gain (1–3 kg)
• Skin changes (acne
• oiliness)
• Digestive changes (constipation or diarrhoea)
• Changes in appetite or food cravings (particularly for sweet or salty foods)

What Causes PMS?

Despite decades of research, the exact mechanisms of PMS remain incompletely understood. Crucially, research has established that women with PMS do not have measurably different hormone levels from women without PMS. The key appears to be differential sensitivity to normal hormonal fluctuations.

Serotonin Hypothesis

The most supported theory is that PMS results from falling estrogen and progesterone in the late luteal phase reducing central serotonergic tone. Estrogen enhances serotonin synthesis, receptor density, and reuptake inhibitor activity. As estrogen drops before menstruation, serotonin availability falls — contributing to low mood, irritability, and carbohydrate cravings (since carbohydrates transiently boost serotonin synthesis via insulin-mediated tryptophan transport).

GABA and Allopregnanolone

Progesterone is converted to allopregnanolone — a neurosteroid that normally enhances GABA-A receptor activity, producing calming, anxiolytic effects similar to benzodiazepines. In most women, rising allopregnanolone in the luteal phase is calming. However, in susceptible women (particularly those with PMDD

Stress Axis

Women with PMDD show altered cortisol awakening responses and disrupted HPA (hypothalamic-pituitary-adrenal) axis regulation compared to controls. Chronic stress and elevated cortisol can amplify PMS symptoms by further impairing serotonin and GABA systems.

Genetics

Twin studies suggest PMS heritability of approximately 30–56%. No single "PMS gene" has been identified, but polymorphisms in serotonin transporter genes and ESR1 (estrogen receptor alpha) have been associated with greater PMS severity.

ACOG Diagnostic Criteria for PMS

Per ACOG (2023

• At least ONE affective symptom (e.g. depression
• irritability
• anxiety
• mood swings) AND at least ONE somatic symptom (e.g. breast tenderness
• bloating)
• Symptoms occur in the 5 days before menses for at least 3 consecutive cycles
• Symptoms resolve within 4 days of menses onset
• Symptoms cause identifiable dysfunction (at work
• at home
• or in relationships)
• Symptoms are not attributable to medications
• another medical condition
• or substance use

Importantly, diagnosis should be confirmed by prospective symptom tracking — ideally using a validated tool such as the Daily Record of Severity of Problems (DRSP) or the Calendar of Premenstrual Experiences (COPE) — over at least 2 consecutive cycles. Retrospective recall is often inaccurate and can confound the diagnosis.

Differential Diagnosis: What Else Could It Be?

• Major depressive disorder or generalised anxiety disorder: Symptoms persist throughout the cycle
• do not remit post-menses
• Bipolar disorder: May have premenstrual exacerbation but with non-cyclic episodes as well
• Thyroid disease: Can cause fatigue
• mood changes
• and cycle irregularity — check TSH
• Iron deficiency anaemia: Causes fatigue and cognitive difficulty throughout the cycle
• Endometriosis: Pelvic pain that may worsen before periods but also occurs at other times
• Perimenopause: Vasomotor symptoms
• sleep disturbance
• and mood changes in women ≥40

References: ACOG Practice Bulletin on PMS/PMDD 2023; AAFP — Premenstrual Syndrome, 2022; Yonkers KA et al., Lancet 2008; DSM-5 on PMDD.