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There are certain risk factors that make you more likely to develop a blood clot. Some of the risk factors are under your control, while others can’t be changed. If you develop symptoms that could indicate a clot, then your medical team will consider your risk factors as part of the process of diagnosis.
The risk factors that are under your control are known as modifiable risk factors. You can take actions to change these factors and reduce your risk of having another clot. Some modifiable risk factors for a clot include:
- Immobility: When you sit or lie down for a long period of time, your blood tends to pool in the veins in your legs and feet. Stagnant blood is far more likely to clot. One of the most important factors in preventing clots is making sure that you keep moving. If you need to be sitting for a long period (such as at work or on a plane), make sure to get up for movement breaks throughout the day.
- Dehydration: Your blood is more likely to clot when you’re dehydrated. Consistently drinking enough water helps to reduce your risk of a clot.
- Smoking: Chemicals found in cigarette smoke make the platelets in your blood more likely to stick together and form a clot. It also damages the lining of blood vessels, which can make a clot more likely to form.
- Obesity: People who are very overweight are more likely to experience blood clots. Those whose body mass index (BMI) falls into the obese category (30 or above) have a blood clot risk that’s two to three times higher than people of normal weight (below 25). It’s believed that this occurs partly due to reduced physical activity, but there are also a variety of metabolic and hormonal changes caused by obesity that make a clot more likely to form.
- Taking hormones such as hormonal birth control pills and postmenopausal hormone replacement therapy which can cause a small increase in the risk of blood clots. It’s important to weigh this risk against the benefits that you receive from taking hormones.
There are also some risk factors that you can’t control. These are known as nonmodifiable risk factors. Some of them include:
- Family history: If you’ve had relatives who experienced blood clots, then you’re more likely to experience one yourself. Even though you can’t change your genetics, it’s useful to know this. If you’re at a higher risk because of your family history, then you may want to focus more on taking actions that will help to reduce your risk.
- Certain medical conditions, including diabetes, cancer, high blood pressure, high cholesterol, or other diseases that cause chronic inflammation.
- Having recently had surgery or experienced physical trauma: This tends to lead to a period of immobility, and certain types of surgical procedures also raise the risk of a clot in other ways, through manipulation of the structures of the body. After surgery or trauma, it’s best to include some movement throughout each day, to reduce your clot risk. Your surgical team will help you to determine safe ways to do this.
Prevention of a first blood clot is known as primary prevention. If you’ve never had a blood clot before, then you’ll be thinking about primary prevention. If you have any of the modifiable risk factors above, then addressing those will help to reduce your risk. If you have nonmodifiable risk factors, then you may want to focus even more on any modifiable risk factors. For example, after having surgery, pay extra attention to getting enough water and including gentle physical movement as much as possible.
If you’ve already experienced a blood clot, then you’ll need to consider how to prevent yourself from having another clot. This is known as secondary prevention. The same actions that work for primary prevention will also help with secondary prevention. In addition, you should ensure that you take any medical treatment exactly as directed. This may include taking medications and wearing compression stockings regularly. You might need regular monitoring of a measurement called INR, to ensure that your blood’s ability to clot is within a safe range. If your medical team recommends this, make sure that you’re diligent about that, as well.