Painful and Irregular Periods: What Is Normal?

Almost every woman I have asked about her periods answers the same way: "normal, I think." Then, two questions later, it turns out she plans her work around day two, keeps a spare pair of trousers at the office, and has taken painkillers every month since she was fifteen.

The difficulty is that nobody can see anyone else's period. Women calibrate against their mother, their sister, and a general instruction to get on with it. So the useful thing is not reassurance. It is numbers you can check yourself against.

What a normal cycle actually looks like#

International consensus definitions, expressed in plain terms:

Two windows in life are legitimately irregular. In the first two to three years after a first period, the brain. Ovary signaling system is still maturing and many cycles happen without ovulation. Before menopause, usually from the mid-forties, cycles typically shorten first, then become erratic and skip. Both are physiology, not disease. Outside those windows, an irregular cycle is information.

How to tell if your bleeding is genuinely heavy#

"Heavy" as a feeling is useless. Here is what to count instead. Any of these, occurring regularly, means heavy menstrual bleeding:

• Soaking through a regular pad or tampon in two hours or less, more than once in a period.
• Doubling up, a tampon plus a pad, because one is not enough.
• Passing clots larger than about 2.5 cm across (roughly a UK ten pence piece, a US quarter, or a large grape).
• Flooding through clothing or onto bedding.
• Having to get up at night to change protection.
• Bleeding for more than eight days.
• Needing to plan your work, travel or social life around the heaviest days.

If you use a menstrual cup, you have a genuine advantage: most are marked in milliliters. Adding up what you empty over the whole period gives you a real number, and a total above 80 mL is objectively heavy.

The wider definition matters too. Modern guidance defines heavy menstrual bleeding as loss that interferes with a woman's physical, emotional, social or material quality of life. You do not have to prove a volume to qualify for help. If your period costs you two working days a month, that is the clinical problem, whatever a measuring jug would say.

Why heavy bleeding happens#

Clinicians use a structured list so that nothing gets forgotten. Broadly it splits into structural causes, things you could see or touch, and non-structural ones.

Structural:

• Fibroids: benign muscle growths in the womb wall. Very common, more so in women of African ancestry; the ones bulging into the cavity cause the heaviest bleeding even when small.
• Polyps. Small overgrowths of the lining, often causing bleeding between periods.
• Adenomyosis: covered below.
• Cancer or pre-cancer of the lining. Uncommon, but the reason new heavy or irregular bleeding after 45, and any bleeding after menopause, is always investigated.

Non-structural:

• Ovulatory dysfunction. No ovulation means no progesterone, so the lining builds unopposed and eventually sheds heavily and unpredictably. This is the mechanism in PCOS, thyroid disease, high prolactin, perimenopause, significant stress and low body weight.
• Bleeding disorders, genuinely under-recognized. Around one in eight women with heavy periods has an underlying clotting disorder, most often von Willebrand disease. The clue is periods heavy since the very first one, often with easy bruising, nosebleeds or heavy bleeding after dental work.
• Endometrial causes. Local problems with the lining's own control of bleeding.
• Medication: anticoagulants, some hormonal treatments, copper coils.

Period pain: the two kinds#

Primary dysmenorrhoea is pain with no underlying disease. When the lining breaks down it releases prostaglandins, which make the muscle contract hard and squeeze its own blood supply. A cramp is briefly a small area of oxygen-starved muscle. Prostaglandins also reach the gut, which is why nausea, loose stools and back pain travel with it. Primary period pain starts within a year or two of the first period, begins with the bleed or just before, and lasts one to three days.

Secondary dysmenorrhoea is pain caused by something else. The pattern is different, and the pattern is the diagnosis:

• Pain that starts days before the bleed.
• Pain that worsened over years, having once been mild.
• Pain that appeared for the first time after the age of 25.
• Deep pain during or after sex.
• Pain opening the bowels or passing urine during a period.
• Pain that does not settle with over-the-counter anti-inflammatories taken properly.
• Pain between periods as well.

Any of those shifts the question from "how do we manage this" to "what is causing this".

Endometriosis#

Endometriosis is tissue similar to the womb lining growing outside the womb. On the pelvic lining, ovaries, bowel, bladder, occasionally further afield. It responds to the same hormonal cycle, so it bleeds, inflames and scars each month with nowhere to drain. Over time that produces adhesions, which stick organs together and generate pain that is no longer neatly cyclical.

It affects roughly 10 per cent of women and girls of reproductive age: around 190 million people worldwide. And it still takes, on average, seven to eight years from first symptom to diagnosis, with published estimates from about four to eleven years depending on the country.

Knowing why that delay happens helps you push against it:

• Pain is normalized, by families, by schools, and sometimes by clinicians.
• Symptoms overlap heavily with irritable bowel syndrome and bladder conditions, so women are treated for those for years.
• Investigations look normal. Ultrasound finds ovarian endometriomas and can detect deep disease in expert hands, but superficial peritoneal endometriosis is invisible on scans, and there is no blood test.
• Disease severity at surgery correlates poorly with pain severity. Someone with minimal visible disease can be in severe pain, and vice versa.

An important update: guidelines no longer require laparoscopy before treatment. A clinical diagnosis can be made from symptoms and examination, and treatment can start on that basis. If you are told "we cannot do anything until you have surgery", that is out of date.

Adenomyosis#

Adenomyosis is endometrial-type tissue growing within the muscular wall of the womb itself. It is the classic combination of heavy and painful. A deep dragging ache, a period that feels like labor, and a uterus that is bulky and tender on examination.

It was long assumed to be a condition of women in their forties who had had children. Better imaging has found it in younger women and women who have never been pregnant. It is diagnosed on transvaginal ultrasound or MRI, and it frequently coexists with endometriosis and fibroids. One reason women get partial answers, when the fibroid is found, treated, and the pain remains.

Thyroid and PCOS: the two most missed causes#

Thyroid disease. An underactive thyroid classically causes heavier, more frequent bleeding, with fatigue, cold intolerance, constipation, dry skin and weight gain. An overactive thyroid causes lighter, less frequent or absent periods, with weight loss, heat intolerance, tremor and palpitations. Both are found on a single TSH test and both are treatable. One of the cheapest tests in medicine and one of the most commonly forgotten in a woman with cycle problems.

PCOS. The most common cause of persistently long or absent cycles. Because ovulation is unreliable, progesterone is not produced regularly, so the lining is not shed on schedule, often long gaps followed by a very heavy bleed. Look for the accompanying features: excess coarse hair in a male pattern, persistent adult acne, hair thinning at the crown, difficulty conceiving, or darkened velvety skin at the neck or armpits.

Other causes of an irregular or absent cycle worth naming: raised prolactin (sometimes with milky nipple discharge or headaches), low body weight or a high training load, significant psychological stress, primary ovarian insufficiency under 40, and, always, always first, pregnancy.

What a doctor will typically check#

A pelvic examination is part of a proper assessment for pain. You can ask for a chaperone, a smaller speculum, another day, or for it to stop at any point.

What actually helps#

Without dosing, and framed as things to discuss with your own doctor:

• Anti-inflammatory painkillers block prostaglandin production, which is the actual mechanism of the pain, and reduce blood loss by roughly 20 to 40 per cent as a bonus. They work far better started at the first twinge than after the pain is established. They do not suit everyone. Stomach ulcers, asthma in some people, kidney disease and certain other medicines all matter.
• Tranexamic acid reduces blood loss by around 40 to 50 per cent by slowing clot breakdown in the womb. Taken only on bleeding days; no effect on pain or hormones.
• Hormonal treatments. A hormone-releasing intrauterine system thins the lining and is the most effective medical treatment for heavy bleeding, commonly cutting loss by 80 to 90 per cent. Combined hormonal contraception and progestogen-only options are alternatives. For endometriosis, treatments that suppress the cycle reduce pain in a large proportion of women.
• Heat. A hot water bottle is not a consolation prize. Trials put continuous low-level heat roughly on par with simple analgesia for period pain, and there is no reason not to use both.
• Regular physical activity has modest but real evidence for reducing period pain.
• Iron replacement where ferritin is low. Treating the bleeding without replacing the iron leaves you tired for months longer than necessary.
• Procedures where medical treatment is not enough: endometrial ablation, removal of fibroids or polyps, uterine artery embolisation, excision surgery for endometriosis, hysterectomy as a definitive option.

Oversold: elimination diets marketed for endometriosis, "womb detox" products, and vaginal steaming, which is at best useless and at worst causes burns.

What I actually see in clinic#

The thing I say most often is some version of: no, that is not normal, and I am sorry nobody told you sooner.

The pattern that stays with me is the woman who has managed severe pain competently for a decade. She has a system. She knows which two days to keep clear, she takes painkillers before the pain starts, she has never made a fuss. She has also never been examined, never had a scan, and has years of undiagnosed disease behind her. Competence at coping is one of the main reasons endometriosis is diagnosed late. Doctors read calm as mild.

The other thing I see constantly is iron: women told their blood count is fine, who are exhausted, losing hair, breathless on one flight of stairs, and whose ferritin, never actually measured, turns out to be in single figures. Hemoglobin is the last domino to fall. Ask for ferritin by name.

At work#

Heavy and painful periods are one of the most common causes of recurrent short-term absence in women of working age, and almost nobody records the real reason on the form.

Some of this is fixable in the workplace rather than the clinic. In manufacturing the barriers are predictable: fixed break times that do not match a day-two flow, distance to toilets on a large site, coveralls that take time to remove, hot environments that worsen dizziness in an iron-deficient woman, and shift patterns that make treatment schedules harder to keep. Each has a straightforward adjustment, and occupational health can arrange most of them without your diagnosis reaching your line manager.

Rotating and night shifts are also associated with more menstrual irregularity, through disruption of the circadian signals that help regulate the cycle. If your periods became erratic within months of starting nights, that connection is real and worth mentioning.

The bottom line#

Normal periods run every 24 to 38 days, last up to eight days, and do not stop you living your life. Heavy means soaking through protection every two hours, clots over 2.5 cm, flooding, or bleeding that costs you days, and you do not need to prove a volume to deserve help. Pain that starts before the bleed, worsens over years, or resists ordinary painkillers points to something treatable, most often endometriosis or adenomyosis, and a normal scan rules out neither. Thyroid disease and PCOS are common, missed and easy to test for. Keep three months of a simple diary, ask for ferritin by name, and do not let a normal ultrasound end the conversation.