Health Insights
Irregular periods: when should you see a doctor?
Periods that come early, late or not at all can have many explanations. Learn which changes are worth discussing with a doctor, what information can help, and when to seek urgent care.
Periods that arrive earlier or later than expected, change in length, or stop for a while are a common reason to see a doctor. Sometimes the explanation is simple; sometimes it needs a closer look.
This article explains which changes are worth discussing, what information can help an assessment and when to seek urgent care. It is general information, not a way to diagnose yourself.
What counts as an irregular cycle?
For adults, an international evidence-based guideline describes cycles as irregular when they are shorter than 21 days or longer than 35 days, or when there are fewer than 8 cycles a year. (2023 International PCOS Guideline, recommendation 1.1.1)
Irregular cycles are normal in the first year after periods start, and different thresholds apply for the next few years. This article focuses on adults. (2023 International PCOS Guideline, recommendation 1.1.1)
Changes worth discussing with a doctor
It may be worth making a routine appointment if:
- 01
your cycles are often shorter than 21 days or longer than 35 days, or you have fewer than 8 periods a year
- 02
your periods have stopped for 3 months or more
- 03
you are younger than 45 and have changes in your periods together with symptoms such as hot flushes or night sweats
- 04
in midlife, your periods have become more frequent or very heavy
- 05
you are bleeding between periods or after sex
- 06
you have any bleeding after menopause
- 07
you are worried about a change in your periods
These reasons are drawn from guidance on irregular cycles, absent periods, perimenopause, bleeding between periods or after sex, and bleeding after menopause. (2023 International PCOS Guideline; Endocrine Society clinical practice guideline; Australasian Menopause Society; Royal Australian and New Zealand College of Obstetricians and Gynaecologists; Cancer Australia)
If your periods are also heavy, heavy periods: what is considered heavy menstrual bleeding? explains what counts as heavy and why it is worth discussing.
Irregular periods are not automatically PCOS or perimenopause
PCOS and perimenopause are possible explanations, but they are not the only ones. Periods can become irregular or stop because of stress, weight loss, intense exercise or eating disorders. Some medicines, including some contraceptives, can change periods, and thyroid conditions or raised prolactin levels can also affect the cycle. (Endocrine Society clinical practice guideline)
If a period is late or has stopped, it is important to check whether you might be pregnant. (Endocrine Society clinical practice guideline)
During perimenopause, it is common for periods to become less frequent or irregular, and perimenopause is usually recognised from symptoms and changes in bleeding pattern. Even so, midlife symptoms are not always due to perimenopause: conditions such as thyroid disorders, anaemia and depression can occur at the same time. (Australasian Menopause Society)
If PCOS is a question for you, PCOS assessment: what to expect at your first appointment explains how it is assessed. If you are in midlife, when should you see a doctor about menopause symptoms? covers the wider picture.
Notes that can help an assessment
A doctor will usually ask about your periods and your general health, including recent changes in weight, eating, exercise and stress, and any medicines you take. (Endocrine Society clinical practice guideline) It can help to note:
- 01
the first day of each period over recent months, if you have it
- 02
any bleeding between periods or after sex
- 03
whether you could be pregnant, and the contraception you use
- 04
medicines, supplements and hormone treatments you take
- 05
recent changes in weight, eating, exercise, stress or sleep
- 06
other symptoms, such as hot flushes, acne, excess hair growth or pelvic pain
You do not need complete records. A rough timeline and a note of what worries you most are a useful start. For general preparation tips, see your first women's health appointment: what to discuss and how to prepare.
How a clinician may decide whether tests are appropriate
Not everyone with irregular periods needs the same tests. A clinician will usually start with your history and symptoms, then consider whether an investigation would help answer a specific question.
A pregnancy test may be considered when a period is late or has stopped. (Endocrine Society clinical practice guideline)
Age can change the approach. For people over 45 with symptoms, hormone blood tests are generally not needed to diagnose perimenopause, because hormone levels can change from day to day; a doctor assesses symptoms and changes in periods instead. For people younger than 45 with menopausal symptoms, a hormone blood test may be considered. (Australasian Menopause Society)
When bleeding is heavy, a doctor may recommend a pregnancy test if there is any chance you are pregnant, and blood tests for iron deficiency and anaemia. Whether other tests, such as an ultrasound, are needed depends on your individual assessment. (Australian Commission on Safety and Quality in Health Care)
Which tests, if any, are appropriate depends on your age, history, symptoms and what is already known. A clinician can explain why a test is or is not suggested.
When to seek urgent care
Some symptoms need urgent care rather than a routine appointment. If you could be pregnant and have any of the following, go to an emergency department as soon as possible, or call Triple Zero on 000 in an emergency:
- 01
vaginal bleeding or spotting
- 02
pain in your lower abdomen or pelvis, particularly if it is on one side
- 03
pain in the tip of your shoulder
- 04
dizziness, light-headedness or a racing heartbeat
These can be signs of an ectopic pregnancy, which can cause internal bleeding that can be life-threatening if not treated quickly. (Royal Australian and New Zealand College of Obstetricians and Gynaecologists)
A change in your cycle is worth a conversation
Irregular periods are common and often have a straightforward explanation, but a change from your usual pattern is reasonable to discuss. An assessment can help clarify what may be contributing and whether anything further is needed.
You can also read about PCOS assessment and care, perimenopause care and heavy menstrual bleeding assessment and care at Mahila.
References
Human Reproduction (2023). Recommendations from the 2023 International Evidence-based Guideline for the Assessment and Management of Polycystic Ovary Syndrome. https://pmc.ncbi.nlm.nih.gov/articles/PMC10477934/ Checked 14 October 2026.
Endocrine Society (2017). Functional hypothalamic amenorrhea: an Endocrine Society clinical practice guideline. Journal of Clinical Endocrinology & Metabolism. https://academic.oup.com/jcem/article/102/5/1413/3077281 Checked 14 October 2026.
Australasian Menopause Society (n.d.). Diagnosing menopause. Information sheet. https://hub.menopause.org.au/Play?pId=f769710e-20f5-4bcf-886a-1fa27d97254e Checked 14 October 2026.
Australian Commission on Safety and Quality in Health Care (2024). Heavy Menstrual Bleeding Clinical Care Standard. https://www.safetyandquality.gov.au/standards/clinical-care-standards/heavy-menstrual-bleeding-clinical-care-standard Checked 14 October 2026.
Royal Australian and New Zealand College of Obstetricians and Gynaecologists (2021). Investigation of intermenstrual and postcoital bleeding. https://ranzcog.edu.au/wp-content/uploads/Investigation-Intermenstrual-Postcoital-Bleeding.pdf Checked 14 October 2026.
Cancer Australia (n.d.). What are the symptoms of endometrial cancer? https://www.canceraustralia.gov.au/cancer-types/endometrial-cancer/what-are-symptoms-endometrial-cancer Checked 14 October 2026.
Royal Australian and New Zealand College of Obstetricians and Gynaecologists (2025). Ectopic pregnancy. Patient information. https://ranzcog.edu.au/wp-content/uploads/Ectopic-Pregnancy.pdf Checked 14 October 2026.
A change in your cycle is worth discussing
A consultation can help you talk through what has changed, what may be contributing and whether any assessment is appropriate for you.