Written & medically reviewed by Dr. Sanjay Anbu, MBBS· Last reviewed
An occasional late or early period is normal, but a pattern of irregular cycles can point to something treatable — from PCOS or thyroid problems to stress, weight change or approaching menopause.
PCOS (polycystic ovary syndrome) — a very common cause
Thyroid problems (under- or over-active)
Significant stress, weight loss or weight gain
Intense exercise or an eating disorder
Perimenopause (in the 40s–50s)
Some contraceptives and other medicines
When to see a doctor urgently
Bleeding between periods or after sex
Very heavy bleeding, or periods lasting more than 7 days
No periods for 3+ months when not pregnant
Periods restarting after menopause
Severe pelvic pain
A pattern is worth checking. Simple tests (like thyroid, hormones and an ultrasound) often find a treatable cause. MedDroid gives general information, not a diagnosis.
Frequently asked questions
What is considered an irregular period?
Cycles that are consistently shorter than about 21 days or longer than 35 days, or that vary a lot month to month. An occasional off month is usually normal.
Can stress delay my period?
Yes — stress, big changes in weight or exercise, illness and travel can all delay or skip a period by affecting the hormones that control your cycle.
When should I see a doctor about irregular periods?
If they are persistently irregular, very heavy, come with bleeding between periods or after sex, or you have no period for 3+ months without being pregnant.
Reviewed by Dr. Sanjay Anbu, MBBS. MedDroid is an AI medical assistant and can make mistakes. It provides general health information, not a diagnosis or medical advice — always consult a qualified clinician. In an emergency, contact your local emergency number immediately.