What Are Irregular Periods?
A menstrual cycle is considered irregular when the time between periods varies significantly from month to month, or when your periods become unusually frequent, infrequent or unpredictable.
The average menstrual cycle lasts around 28 days, although anywhere between 21 and 35 days is considered normal for most adults. A cycle that regularly falls outside this range or changes noticeably from your usual pattern may be described as irregular.
Irregular periods can affect women and people who menstruate of any age but are particularly common during adolescence and perimenopause.
What Causes Irregular Periods?
There are many possible causes of irregular periods, ranging from temporary lifestyle factors to underlying medical conditions.
Hormonal Changes
Hormonal fluctuations are one of the most common causes of irregular periods. These occur naturally during puberty, after pregnancy, after stopping contraceptives and while approaching menopause.
PCOS is a common hormonal condition that can cause irregular or absent periods, acne, excessive hair growth and difficulty becoming pregnant.
Polyendocrine metabolic ovarian syndrome (PMOS)
PMOS ( formally known as PCOS) is a common hormonal condition that can cause irregular or absent periods, acne, excessive hair growth and can sometimes be linked with fertility issues.
Stress
Physical or emotional stress can temporarily affect the hormones that regulate the menstrual cycle, leading to delayed or missed periods.
Weight Changes
Significant weight loss and weight gain or excessive exercise can all disrupt normal hormone production and affect ovulation.
Thyroid Disorders
Both an underactive thyroid (hypothyroidism) and an overactive thyroid (hyperthyroidism) can lead to changes in menstrual frequency and flow.
Pregnancy
A missed period is often the earliest sign of pregnancy. Anyone who is sexually active and experiences a missed period should consider taking a pregnancy test.
Contraception
Starting, stopping or changing hormonal contraception may cause temporary irregular bleeding while your body adjusts.
Other Medical Conditions
Less commonly, irregular periods may be associated with:
- Premature ovarian insufficiency (early menopause)
- Hyperprolactinaemia
- Chronic medical conditions such as diabetes
- Certain medications
- Uterine polyps or fibroids
- Rarely can be associated with gynaecological cancers
What Are the Common Symptoms of Irregular Periods?
Symptoms may include:
- Periods occurring less than every 35 days or more frequently than every 21 days.
- Missed periods.
- Unpredictable menstrual cycles.
- Very light or very heavy bleeding.
- Bleeding between periods.
- Spotting after sexual intercourse.
- Periods lasting much longer or shorter than usual.
- Difficulty predicting when your next period will occur.
Depending on the underlying cause, you may also experience:
- Acne.
- Excess facial or body hair.
- Pelvic pain.
- Weight changes.
- Hot flushes or night sweats.
- Difficulty becoming pregnant.
How Are Irregular Periods Diagnosed?
Our Online GP will ask about your menstrual history, medical history, lifestyle and any medications you take.
They may ask:
- When your periods became irregular.
- How often your periods occur.
- Whether you have missed any periods.
- If you experience heavy bleeding or severe pain.
- Whether there is any chance you could be pregnant.
- Whether you are trying to conceive.
- Any recent changes in weight, exercise or stress levels.
Online Assessment
An online GP consultation can help assess your symptoms, identify possible causes and recommend appropriate investigations or treatment.
In-Person Assessment
Depending on your symptoms, further investigations may include:
- Blood tests to assess hormone levels and thyroid function.
- Blood tests for diabetes or other medical conditions if indicated.
- Pelvic ultrasound scan or MRI scanning.
- Referral to a gynaecologist or endocrinologist if further assessment is required.
How Long Do Irregular Periods Last?
The duration depends on the underlying cause.
- Hormonal changes during puberty or perimenopause may continue for several months or years.
- Irregular bleeding after starting hormonal contraception often settles within three to six months.
- Lifestyle-related irregularities may improve once stress, weight or exercise levels are addressed.
- Medical conditions such as PCOS or thyroid disorders usually improve once appropriate treatment has been started.
If irregular periods persist for more than three months or are accompanied by other concerning symptoms, it is important to seek medical advice.
How to Feel Better and Recover Quickly
Self-Care at Home
While treatment depends on the underlying cause, the following may help support menstrual health:
- Maintain a healthy weight.
- Eat a balanced, nutritious diet.
- Exercise regularly but avoid excessive physical training.
- Manage stress through relaxation techniques, mindfulness or counselling if appropriate.
- Keep a record of your menstrual cycle using a diary or period tracking app.
- Take a pregnancy test if there is any possibility you may be pregnant.
Treatment from a GP
Treatment will depend on the cause of your irregular periods and whether you are planning a pregnancy.
Your GP may recommend:
- Hormonal contraception to help regulate your cycle.
- Treatment for PCOS such as Metformin.
- Medication to treat thyroid disorders.
- Referral for fertility assessment if you are struggling to conceive.
- Further investigations if an underlying gynaecological condition is suspected.
When Referral Is Needed
- The cause of your irregular periods is unclear.
- PCOS, endometriosis or premature ovarian insufficiency is suspected.
- You are experiencing fertility problems.
- Imaging or specialist investigations are required.
- There is concern about an underlying abnormality affecting the uterus or ovaries.
When to Seek Urgent Medical Help
Seek urgent medical attention by attending your nearest Emergency Department or contacting NHS 111 if you experience:
- Heavy vaginal bleeding causing dizziness, fainting or weakness.
- Severe pelvic or abdominal pain.
- Heavy bleeding during pregnancy or after a positive pregnancy test.
- Fever with pelvic pain and abnormal vaginal discharge.
- Sudden severe pain with vomiting, which could indicate an ovarian emergency.
You should also arrange an urgent GP appointment if you develop bleeding after menopause, bleeding after sex, or persistent bleeding between periods, as these symptoms require prompt assessment.
How Dr.Online UK Can Help
Our UK-registered GPs can assess irregular periods through a convenient online consultation.
We can:
- Offer same-day online GP appointments.
- Discuss your symptoms and possible causes.
- Arrange appropriate blood tests or investigations where required.
- Prescribe treatment when clinically appropriate.
- Provide private prescriptions.
- Issue fit notes if your symptoms are affecting work.
- Arrange referral letters for specialist assessment where needed.
- Offer ongoing advice and support to help you manage your menstrual health.
