What causes premenstrual syndrome?

Changes in ovarian hormones after ovulation may affect brain chemicals involved in mood, sleep and appetite. The exact response differs from person to person, which helps explain why PMS can feel mild in one person and disruptive in another.

PMS symptoms usually follow a repeating pattern: they develop after ovulation, during the phase before a period, and improve once bleeding begins or shortly afterwards. This timing is more informative than any single symptom.

Hormone shifts can influence fluid balance, breast tissue, digestion and the nervous system. PMS can therefore present with bloating, breast tenderness, headaches, tiredness, food cravings, irritability, low mood, anxiety or difficulty concentrating. Stress, poor sleep and existing mood symptoms may make the experience harder, but they do not mean the symptoms are imagined or caused by personal weakness.

Symptoms that occur throughout the month may have another explanation or may reflect a condition that becomes worse before a period. Keeping track of timing helps a clinician distinguish PMS from thyroid problems, anaemia, pregnancy-related changes, medication effects, depression or anxiety.

Record symptoms and bleeding dates across several menstrual cycles. Include mood, sleep, pain, appetite, daily functioning and when each change settles. A consistent premenstrual pattern can guide the assessment and show which symptoms need the most attention.

Regular movement, balanced meals, dependable sleep and limiting triggers that clearly worsen your symptoms may help. If symptoms interfere with work, education, relationships or usual activities, a clinician can discuss treatment matched to the main concern. Options may include psychological support, medicines that affect serotonin, or hormonal contraception such as the combined pill when medically suitable.

Arrange a routine appointment if symptoms repeatedly disrupt daily life, are becoming more severe, occur outside the premenstrual phase, or do not improve with self-care. Bring your symptom record and a list of medicines, supplements and contraceptives so the clinician can look for other contributors.

Seek urgent help if you feel unable to keep yourself safe, have thoughts of self-harm or suicide, or develop sudden severe symptoms such as chest pain, fainting, marked shortness of breath or unusually heavy bleeding. These warning signs need prompt assessment regardless of where you are in your cycle.

Ask whether the timing fits PMS, whether another health condition or medicine could be contributing, and which treatment best matches your most disruptive symptom. If hormonal contraception is being considered, ask about personal factors that may make it unsuitable, including migraine with aura, blood-clot history, smoking and high blood pressure.