What counts as heavy menstrual bleeding?
Before I start to explain the reasons why periods can suddenly get heavier, I thought it would be useful to examine what defines a period as heavy in the first place
Going quickly through the box of tampons or pads
The first thing to consider is the amount of sanitary products you have to use during the course of your period. If you have to change your sanitary pad or tampon every hour or two then this can definitely not be considered normal. Also, if you find yourself needing double sanitary protection, so having to use more than one sanitary product at the same time, in order to protect yourself from leakages then again, this can be deemed as heavy menstrual bleeding.
Lots of leakages
If leakages from heavy bleeding, known as flooding, are a common occurrence for you then this may also indicate that your period is heavy, and a heavy menstrual flow can be associated with clots too. However, do bear in mind that the strength of your chosen sanitary product may just be inadequate for your blood flow.
A long period
Another thing to consider here is the length of your period. It is normal for periods to last anywhere between three and seven days, but if yours lasts beyond this it's an indicator that things are a little heavier than they should be. This may also coincide with a shorter menstrual cycle (more frequent periods).
Large blood clots
Most women pass some blood clots during the course of their periods so the key here is the size. If yours are regularly bigger than a 10 pence piece then it suggests your period is overly heavy and this could be classed as a type of abnormal uterine bleeding.
Signs of anaemia
Anaemia occurs when your blood lacks red blood cells or haemoglobin and so it often comes about as a direct result of heavy bleeding. Anaemia as a result of bleeding disorders or heavy menstrual bleeding could lead on to cause symptoms such as fatigue, shortness of breath, heart palpitations and pale skin, so is definitely something to look out for if you think your periods are heavy.
Lots of blood
Many women are preoccupied with how much blood they are losing each month and although this can indicate whether or not your period is heavy, the factors above must be considered as well.
As a rule though, most women lose less that 16 teaspoons of blood during the course of their periods and the average is 6 to 8 teaspoons. A heavy period is anything more than this but, as we don't measure the amount of blood coming out, this isn't the most accurate way to determine if your period is heavy or not. With experience though, most women can tell what a normal period is and what is not.
Reasons for heavy periods
Now you know what is classed as a heavy menstrual bleeding, let's take a look at 6 reasons which could be causing you to experience heavy periods:
1. Changes to weight
As I discussed extensively in my blog ‘Could your weight be affecting your periods?', gaining weight could potentially cause heavy menstrual bleeding. This is partly because fat cells hold oestrogen which they then release into the rest of our body. This can result in oestrogen dominance, a problem that is characterised by heavy periods, painful breasts, bloating, irritability and mood swings.
Losing lots of weight on the other hand, can lead to a shortage of oestrogen and as a result symptoms such as low mood, irregular bleeding, or light, infrequent periods (as a result of a thinner uterus lining) can become problematic.
2. New medications
Medications come with all sorts of side effects but sometimes they can even influence menstrual cycles and give rise to heavy menstrual bleeding. I've listed a few common culprits below.
Aspirin
Although this has a number of uses, aspirin is most commonly used for pain relief. In fact, many women call upon it to ease their period cramps however, aspirin has blood thinning properties which can risk contributing to very heavy bleeding.
Anticoagulants
These medications are used to prevent blood clots but, you've guessed it, they can also risk contributing to heavy blood flow or blood loss.
3. Changes to your birth control
I have written about methods of contraception in previous blogs but here I focus on how changing birth control methods can affect the amount you bleed with each menstrual cycle.
Contraceptive patch and the pill
These contraceptives usually result in a lighter flow and help to reduce heavy periods and bleeding, so if you've recently stopped using either of them you may experience more heavy menstrual bleeding, once more.
The non-hormonal coil
This common contraceptive is non-hormonal, intrauterine device, an alternative to birth control pills, and is commonly referred to as the 'copper coil.' It is inserted in the uterus by a doctor or nurse to stop you getting pregnant. Although it is very effective and can last for years, it can come with the unfortunate side effect of heavier or more painful periods. However, if these syptoms persist you could always make another appointment to have this checked by your doctor. They may have to conduct a physical exam, a pelvic exam in order to decipher if the coil has been inserted correctly.
There is an alternative, hormonal coil known as the Mirena coil which can offer some hormonal support, and in some cases, make periods much lighter, shorter, or can even cause them to disappear completely.
Therefore, heavy menstrual bleeding after insertion of a coil should only be a temporary problem and things should settle down after a few period cycles.
4. An underlying condition
If you are experiencing excessive or heavy bleeding, it's important that you don't try to self-diagnose. Instead a trip to your doctor will help to confirm or exclude any of the bleeding disorder issues as mentioned below. Your doctor can take your full health history and heavy period bleeding symptoms into consideration, in order to help rule out any blood clotting disorders or similar health problems characterised by heavy menstrual bleeding.
They can also conduct a physical examination or a blood test, as required, if there is a need to learn more, or rule out other scenarios such as miscarriage or ectopic pregnancy complications which could also give rise to sudden or heavy bleeding.
Dysfunctional uterine bleeding (DUB)
This common condition comes about as a result of an imbalance in hormone levels. It can cause menstrual flow to occur outside the usual period of menstruation, as well as very heavy menstrual bleeding.
DUB can happen at any time - so younger women of reproductive age may suffer too, but it is generally most common after the age of 40.
Uterine fibroids
These are non-cancerous growths that develop in or around the uterine cavity. It is unclear exactly why these growths develop, though it may be linked to an increase, or drop in oestrogen levels. It is common amongst fertile women and causes, amongst other things, pain, sometimes severe pain, constipation and heavy menstrual bleeding.
Uterine polyps are similar growths to fibroids which may also develop in the uterus wall in a similar way, and give rise to similar symptoms in terms of the menstrual bleeding. A painless test such as an ultrasound scan may help to diagnose some of these conditions.
Underactive thyroid
This condition occurs when the thyroid does not produce enough hormones, causing symptoms such as weight gain, feeling tired and feelings of depression. However, the condition is also associated with more painful or heavy menstrual bleeding. Your doctor would help confirm this as a likely cause of your heavy menstrual bleeding, with the help of blood tests. They could also conduct any other tests, and also based on your medical history, help rule out any thyroid disease, for example.
Adenomyosis
This occurs when the lining of the uterus becomes embedded in the wall of the womb. It causes painful periods as well as heavy menstrual bleeding, (you may also pass clots) and more blood lost, as a result, each month.
Please note, you should always contact your doctor if you struggle with heavy bleeding, suspect you are suffering from bleeding disorders, but you haven't yet been diagnosed.
Bleeding disorders
Bleeding disorders such as von willebrand disease should also be ruled out. Symptoms here could include heavy or long menstrual bleeding as well as other symptoms such as bleeding between periods or other more general, excessive bleeding complaints.
5. PMS
Premenstrual syndrome is characterized by a range of symptoms including heavy periods, irritability, fluid retention and painful periods. Unfortunately, the exact cause of PMS is unclear though it is probably to do with an imbalance in the ratio of progesterone and oestrogen in the body. Also, things like diet and stress are known to worsen symptoms as these can also affect hormones and your menstrual flow.
6. Menopause
Hormone levels fluctuate as you approach the menopause and this, perhaps a little surprisingly, can also contribute to heavier periods. Heavy cycles are more likely to develop just before the menopause when the body eases out of reproductive mode and oestrogen levels peak. This is usually accompanied by irregular periods and feelings of exhaustion.
Eventually, lighter periods should replace the heavy periods, before you will eventually stop bleeding all together, but if this takes a while to materialise, some action may need to be taken sooner in order to help manage your symptoms.
If you'd like some more information on the menopause then our expert Eileen has a multitude of blogs on the subject. Click the link to find her most recent ones.
Please note, in many cases menopause can be successfully managed through diet, lifestyle and supplement picks. In some cases, additional treatment options may be offered, if felt necessary, including an endometrial ablation, for example, in order to strip the lining of the uterus and therefore treat heavy period bleeding.
In even rarer cases, such as in the case of persistent or excessive bleeding, some women may need to have a more major operation, such as a partial or full hysterectomy, in order to help manage heavy menstrual bleeding disorders, as a result of extreme hormone imbalances during menopause. This will help to ensure extreme blood loss doesn't continue.
How to reduce bleeding?
If you have one heavy period, it can be common to experience these infrequently and there may be no need to consult your GP. However, if you experience a persistent change with heavy menstrual bleeding and blood loss for three months or more, you should consult your doctor.
Also, the NHS state that if you are experiencing other symptoms such as severe cramp and bleeding between periods, then a doctor will be able to see if there is an underlying cause for this.
Some common, conventional treatments for heavy periods, or in a bid to reduce pain, include contraceptives though. However, for a number of reasons, some women don't want to go down the route of contraceptives just to try and reduce menstrual bleeding.
Instead, if appropriate, a herbal remedy such as Agnus castus may be used to help address heavy menstrual blood loss associated with PMS.
Please note however, that Agnus castus cannot be used alongside hormonal contraceptives.
Originally published in September 2018, updated and reviewed in May 2024.
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Originally published in September 2018, updated and reviewed in May 2022.
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