Haemophilia, severity, and bleeding episodes
Understanding the severity of haemophilia
The information here is not intended as a substitute for medical advice. If you have any concerns or queries regarding haemophilia, please speak to your doctor, pharmacist, or nurse
Why do bleeds happen?
Haemophilia is a rare bleeding disorder where the blood does not clot as well as it should. This happens because the body does not have enough of a protein called a clotting factor, which helps bleeding stop.1
There are different types of haemophilia. The type someone has depends on which clotting factor is affected, and how much of it is in their blood.
The two main types are:1
Haemophilia A
This is when the body does not have enough clotting factor VIII, also known as factor 8.
Haemophilia B
This is when the body does not have enough clotting factor IX, also known as factor 9.
Haemophilia can be described as mild, moderate or severe. People with severe haemophilia may need more regular treatment and have a higher risk of serious bleeding, including bleeding that can be life-threatening.1
Females can also be affected by haemophilia.2
What do factor levels tell us?
Factor levels can help show the severity of haemophilia; in general, the lower the level of clotting factor a person has in their blood, the more bleeding they will have without treatment1,2
Factor levels <1% (Severe haemophilia) 2
Significant risk of bleeding, which occurs frequently, even with minor injuries or sometimes with not injury at all (spontaneous bleeding). Joint and muscle bleeds are common, and internal bleeding can happen in various tissues of the body.
Factor levels between 1–5% (Moderate haemophilia)2,3
Occasional spontaneous bleeding is possible. Excessive bleeding may occur after trauma. Bleeding may be triggered by injuries that would normally cause only minor bleeding in people without haemophilia.
Factor levels between 5–<40% (Mild haemophilia)2
Spontaneous bleeding is rare. Bleeding may occur after significant trauma or surgery.
Factor levels >40% (Normalised haemostasis)3
With appropriate care, factor levels in the blood may increase and may become similar or the same as a person without haemophilia.4
Types of bleeds in haemophilia
People with haemophilia can experience different types of bleeding. Some bleeds are easy to see, while others happen inside the body and may be harder to notice.
External bleeding
This is bleeding that happens on the outside of the body or in the mouth. It can happen after a cut, scrape, nosebleed, or from biting the inside of the mouth, lips or tongue.5
Internal bleeding
This is bleeding that happens inside the body. In haemophilia, this most commonly affects the joints and muscles, but it can also happen in other soft tissues.5
Bleeding after surgery or dental treatment
People with haemophilia may have a higher risk of bleeding after an operation, procedure or dental treatment. Your haemophilia care team can help plan treatment before and after any procedure to reduce this risk.6
Spontaneous bleeding
Sometimes bleeding can happen without an obvious injury or cause. This is known as a spontaneous bleed.7
Silent bleeds
Silent bleeds are small internal bleeds that may not cause obvious symptoms at first. They can still lead to damage over time, particularly if they happen in the joints.8
What are silent bleeds?
Silent bleeds are small bleeds inside the body that may not cause obvious symptoms at the time. In haemophilia, these bleeds can happen in places such as the joints or muscles. Over time, repeated bleeding into a joint may affect joint health, even when a person is not noticing regular bleeds.8 This is one reason why protecting long-term joint health is an important part of haemophilia care.
It's important to understand how to detect silent bleeds, as they can cause lasting harm and make it harder to move and perform daily activities.8
Spotting silent bleeds can be difficult, as they do not occur with symptoms. Your doctor should periodically assess your joint status to identify any abnormalities that can be caused without an observed bleed and may carry out a physical examination to help identify signs of bleeding. They may also use imaging tools such as ultrasound or magnetic resonance imaging (MRI) which can detect joint abnormalities that are not visible externally.8
Managing a bleed in haemophilia
When a bleed happens, it's important to treat it right away to reduce the risk of health complications and disruptions to school, work and family life.9
Bleeds can be managed by using First Aid steps known as POLICE - this stands for Protection, Optimal Loading, Ice, Compression and Elevation.10 Ask your healthcare provider about these steps.
For severe bleeds, immediate treatment is necessary. This will likely involve clotting factor replacement therapy, where additional clotting factor is given through an injection to help the blood clot properly and stop the bleed.10 In addition, other treatments may be used to help manage the consequences of bleeding, including pain relievers and supportive care such as physical therapy to aid in recovery.10
- NHS. Haemophilia. Available at: https://www.nhs.uk/conditions/haemophilia/. Last accessed June 2026
- The Haemophilia Society. Types of Haemophilia. Available at https://haemophilia.org.uk/bleeding-disorders/haemophilia-a-and-b/types-of-haemophilia/. Last accessed June 2026
- Malec, L. Matino, D. Targeting higher factor VIII levels for prophylaxis in haemophilia A: A narrative review. Haemophilia. 2023, 1-11.
- Holme, P. et al: Moving towards Noramlization of haemostasis and health equity: Evolving treatment goals for haemophilia A. Haemophilia. 2024.
- National Bleeding Disorders Foundation. Types of bleeds. Available at: https://www.bleeding.org/bleeding-disorders-a-z/overview/types-of-bleeds. Last accessed June 2026
- Kleiboer B, Layer MA, Cafuir LA, Cuker A, Escobar M, Eyster ME, et al. J Thromb Haemost 2022;20(4):857–865.
- Mayo Clinic. Hemophilia. Available at: https://www.mayoclinic.org/diseases-conditions/hemophilia/symptoms-causes/syc-20373327#. Accessed February 2025.
- Gooding R, Thachil J, Alamelu J, Motwani J, Chowdary P. J Blood Med 2021:12:209–220.
- The Haemophilia Society. Treating and Managing a Bleed. Available at: https://haemophilia.org.uk/bleeding-disorders/haemophilia-a-and-b/treating-managing-a-bleed/ Last accessed June 2026
- Srivastava A, Santagostino E, Dougall A, Kitchen S, Sutherland M, Pipe SW et al. Haemophilia 2020;26(Suppl 6):1–158.
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July 2026