Premenstrual syndrome (PMS / PMDD)
A cluster of physical and emotional symptoms that appear in the days before a period and settle once it starts. Common ones include mood changes, irritability, bloating, breast tenderness and tiredness. When mood symptoms are severe, it is called premenstrual dysphoric disorder (PMDD).
What it is
Premenstrual syndrome (PMS) is a recurring set of physical and emotional symptoms that appear in the second half of the menstrual cycle — the week or two before a period — and reliably improve once bleeding begins. It is thought to arise not from abnormal hormone levels but from a sensitivity to the normal cyclical rise and fall of estrogen and progesterone after ovulation, and how these interact with brain chemicals such as serotonin. PMS is very common, and symptoms range widely: emotionally, irritability, mood swings, anxiety, low mood, tearfulness and difficulty concentrating; physically, bloating, breast tenderness, headaches, fatigue, food cravings, joint or muscle aches, and disturbed sleep. What defines PMS is the timing — symptoms that recur in the luteal phase and resolve with menstruation — rather than the symptoms themselves. When the emotional symptoms are severe enough to seriously disrupt work, relationships or daily life, the condition is called premenstrual dysphoric disorder (PMDD), a more severe form recognised as a distinct diagnosis. PMS and PMDD are diagnosed from the pattern, ideally by tracking symptoms across at least two cycles in a diary, rather than by a blood test. Tests such as thyroid function may be used to rule out other conditions that can mimic or worsen the picture.
Key lab markers
- No blood test diagnoses PMS or PMDD — the diagnosis rests on the cyclical timing, ideally tracked in a symptom diary over two or more cycles.
- TSH (thyroid function) — checked to exclude a thyroid disorder that can cause overlapping mood and fatigue symptoms.
- Estradiol and progesterone — not diagnostic (levels are typically normal), but part of the reproductive-hormone context.
- Hemoglobin / ferritin — sometimes checked when heavy periods and fatigue coexist.
Symptoms
- Irritability, mood swings, anxiety or low mood in the days before a period
- Tearfulness and difficulty concentrating
- Bloating and abdominal fullness
- Breast tenderness
- Headaches
- Fatigue and disturbed sleep
- Food cravings and appetite changes
- Joint or muscle aches
- Symptoms that reliably ease once the period starts
- In PMDD: severe mood symptoms that disrupt daily life
Related lab panels
When to discuss with a doctor
See a doctor if premenstrual symptoms are disrupting your work, relationships or wellbeing, if low mood or anxiety before periods is severe (which may indicate PMDD), or if you are unsure whether the pattern is truly premenstrual. Tracking symptoms in a diary across two or more cycles is the most useful step and helps confirm the cyclical timing. Any thoughts of self-harm around periods need urgent help. There are effective approaches, from lifestyle measures to specific medications. Blood tests do not diagnose PMS but may be done to rule out other causes such as a thyroid problem. Mediora.AI can help by surfacing results such as thyroid function or anaemia that might be contributing to fatigue or mood, but PMS and PMDD are diagnosed from the symptom pattern with your doctor.