Menstruation varies from person to person, making it harder to distinguish normal from excessive blood loss.
What is a normal menstrual flow?
The usual length of menstrual bleeding is 4 to 6 days. The most common amount of menstrual flow measured in a whole period is around two tablespoons (30 ml) (1,2), the equivalent of soaking around one to seven normal-sized pads or tampons over the course of one period. However, the amount of flow is highly variable, often depending on a person’s stature, if they’ve had children and age.
In most cases, the duration of a cycle will be the same during one’s lifetime. However, it may be influenced by a number of factors such as significant weight changes, dieting, changes in exercise routines, travel, or other disruptions in your daily life.
What is considered a heavy flow or menorrhagia?
Officially, a flow of more than 80 ml (or 16 soaked period products) per menstrual period is considered menorrhagia. Most women bleeding this heavily will have a low blood count (anaemia) or evidence of iron deficiency.
Blood loss can be very hard to measure unless you use a menstrual cup, and even if you lose less than 80 ml, it can still affect your quality of life, so the definition of heavy flow can be adjusted to “excessive menstrual blood loss which interferes with a woman’s physical, social, emotional and/or material quality of life.”(National Institute for Health and Care Excellence – NICE).
How do hormones affect our mental and emotional wellbeing? Click here to learn more
Signs and symptoms of heavy periods:
Diagnosing heavy periods isn’t always easy and women can often have the odd heavy one and then return to normal again. Below we outline some signs to look out for. If these are occurring more often than not, then it might suggest that your periods are heavy.
How much blood you lose:
The amount of blood loss per period is the obvious indicator of how heavy your period is. Periods are considered heavy if you lose more than 60 – 80ml per period (approximately 3 – 5 tablespoons). However, unless you have a tablespoon handy… this might be hard to measure. Generally, if you are having to change your pad or tampon every hour for several consecutive hours then this is classed as a heavy period.
Flooding is a heavy surge of blood loss that often results in you soaking through your period product and onto your clothes or bedding. This shouldn’t happen for an extended period of time or you can become anaemic very quickly. Frequent flooding suggests you have heavy periods.
Note – make sure you are choosing the right period products for you. If the shape or size is wrong, you could leak as a consequence and confuse this for flooding.
Changing your period product during the night:
Generally having to get up during the night to change your period products can suggest you have a heavy flow.
During the night gravity means blood loss should be even slower, although flooding is more likely to occur when you stand up after a night’s sleep if your periods are particularly heavy.
Try avoiding intense exercise, hot baths, and the sauna in order not to increase the flow during sleep.
Note – make sure not to use tampons while you sleep.
Passing red blood clots is also a sign of heavy periods. Your period is a result of the lining of your womb being broken down and passing out through your vagina. As the lining is shed, your body releases anticoagulants to thin this material and prevent blood clots. However, if your period is very heavy, your body struggles to keep up with the rate at which your lining is being shed and as a result, you may find and you pass some blood clots. These clots should be dark red in colour and if other colours make an appearance such as pink or grey, it may be a sign of something else.
For people who notice clots as big as or larger than 2 pence piece (£2p) for more than two periods a year, it is advised to speak to a doctor about this. They will work with you to determine what’s causing these symptoms and how to best move forward.
Length of your period:
The total time you bleed is an indication of how heavy your flow is. If you are bleeding for 7 days or more rather than the average 4 or 5, then you are bound to be losing more blood overall and you will most likely be having heavier periods.
Often described as period cramps, are a result of prostaglandins which are produced in order to initiate contractions of your womb and allow the lining to be shed. Generally, the thicker the lining to be shed, the more prostaglandins there are and the heavier the period will be as a result. If your period pains are particularly severe, it is advised you pay your doctor a visit for a checkup.
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How can I figure out how much I am bleeding?
If you use a menstrual cup, you can easily check how much you are bleeding each day. Otherwise, knowing that one normal-sized period product (tampon, pad), holds about a teaspoon of blood (5ml), the easiest way is to record how many regular sized period products you use each day of your period. Make sure to record how many were half full and multiply by 0.5.
How does abnormal bleeding feel on a daily basis?
Your flow is heavy if:
- Soaks through your tampon or pads every hour for a few hours in a row
- You need to change pads or tampons during the night
- You collect more than 30ml of blood in your menstrual cup
- You fully soak 6 or more regular ( or 3 or more super) pads/tampons
Your flow is medium if:
- You use between two and five regular (two or more super) pads/tampons (fully soaked)
- You collect between ten and 25ml of blood in your menstrual cup
Your flow is light if:
- You use between one and two regular pads/tampons (fully soaked)
- You collect between 5 and 10 ml of blood in your menstrual cup
Your flow is very light if:
- Pantyliners are sufficient for preventing leakage
- You collect less than 5ml of blood in your menstrual cup
Period tracking and why is it important? Click here to learn more
What are the causes of heavy periods?
Heavy flow is most common in the teens and in perimenopause—both are times of the lifecycle when estrogen levels tend to be higher and progesterone levels to be lower.
Understanding the possible cause behind your heavy periods can help you figure out the best way to approach it.
Pre-menstrual syndrome (PMS) is a range of physical, mental and behavioural symptoms which women often suffer in the week or two leading up to their periods. Many of the symptoms of PMS, in particular feeling angry, irritable, having mood swings, sore breasts and experiencing painful, heavy periods are actually a result of a hormone imbalance such as high levels of oestrogen
Fibroids are non-cancerous tumours in the womb that form from muscle and fibrous tissue. In some cases, fibroids don’t give rise to many symptoms; however, in other cases, they can give rise to very heavy, painful periods. Fibroids often form as a result of a hormone imbalance
Hormone imbalance is one of the most common causes of heavy periods. There are two female sex hormones that are particularly important in the menstrual cycle: oestrogen and progesterone. At different times of the month, these hormones are required to be higher or lower. However, if the levels remain elevated when they shouldn’t the higher levels of oestrogen can give rise to heavy, painful periods.
Although age isn’t directly related to heavy or light periods, women are often more prone to hormone imbalances at certain times in their lives. For example, teenagers who haven’t long started their periods, or women approaching menopause are more likely to have bigger fluctuations in their hormones. This means heavier periods may become apparent but are most likely to settle down over time.
Although oral contraceptives and the intrauterine device (IUD), also called the coil, can make your periods lighter or non-existent, in some cases (more likely to be oestrogen-based versions), they can make your period heavier. Other medications, such as blood-thinning medication can also affect your flow. If your periods change suddenly after starting any medication, always refer back to the product information leaflet (PIL) for more information or contact your GP.
Endometriosis is when small sections of the womb end up outside of the uterus, for example in the fallopian tubes, ovaries or vagina. Endometriosis often gives rise to painful, heavy periods.
Other medical conditions:
There may be other conditions that can cause heavy periods such as pelvic inflammatory disease (PID), blood disorders, thyroid issues or cancer of the uterus or ovaries. If your periods change suddenly or are particularly heavy or painful, always be sure to pay a visit to your doctor
What can I do to manage a very heavy flow?
Keep a record:
Make a careful record of your flow and how you are feeling. You can keep a diary or use one of the many apps available to help you track your menstrual bleeding and how you are feeling.
Note – if your flow is so heavy that you start to feel faint or dizzy when you stand up, you should make an appointment to see your doctor.
Ibuprofen (over the counter anti-prostaglandin) can decrease flow by 25-30% and will also help with menstrual cycle-like cramps(3). Take a dose of 200mg ibuprofen tablet every 4-6 hours.
Treat blood loss with extra fluid and salt:
Any time you feel dizzy or your heart pounds when you get up from lying down it is evidence that the amount of blood volume in your system is too low. To help that, drink more and increase the salty fluids you drink.
Supplement with iron:
Ideally, you should get blood tests done regularly, however, if you’ve had a heavy flow for a number of cycles, start taking an over-the-counter tablet of iron (like 35 mg of ferrous gluconate) a day. You can also increase the iron you get from foods—red meat, liver, egg yolks, deep green vegetables and dried fruits like raisins and prunes are good sources of iron.
Supplement with magnesium:
Magnesium is excellent for heavy periods. Magnesium acts as a gentle muscle relaxant and so can help take the edge off very strong contractions of the uterus which can give rise to very heavy periods. Try incorporating plenty of magnesium-rich foods into your diet including dark leafy veg, nuts, seeds, beans and whole grains.
Some people find that relaxation techniques or yoga can help relax the pains associated with heavy flows.
Double up on your period products:
Make sure you are using the right products for your flow, as period products come in different shapes and absorbencies. If you’re worried about leakage, buy plenty of supplies. Have overnight pads on hand and make sure not to use a tampon while you sleep. It’s also a good idea to have an extra set of clothes, underwear, bedsheets, towels to protect where you’ll be sitting or lying down.
In conclusion, if you suspect you might have HMB, contact your doctor for a checkup. This condition is easily treated in most cases and, as with most medical conditions, early detection and diagnosis will make treatment more successful and less invasive.
If you are still unsure if you have HMB, try to track more details during your next cycle, and analyse it afterwards. If you note any of the signs we have mentioned here, book an appointment with your healthcare provider.
- Hallberg L. Menstrual blood loss. Acta Obstet Gynecol Scand 1966; 45:320.
- Cole SK Sources of variation in menstrual blood loss. J Obstet Gynaecol Br Commonw 1971; 78:933.
- Fraser IS Treatment of menorrhagia with mefenamic acid. Obstetrics and Gynecology 1983; 61:109.