Blood clots form when blood thickens and sticks together more than it should. This can be normal and helpful (like stopping bleeding from a cut), but it becomes dangerous when clots form inside blood vessels.
🩸 Main causes of blood clots
1. 🛑 Slow or restricted blood flow
Blood is more likely to clot when it moves slowly:
- Long bed rest or hospitalization
- Long travel (flights, car rides)
- Sitting still for many hours
2. 🩹 Injury or surgery
Damage to blood vessels triggers clotting:
- Surgery (especially legs, hips, abdomen)
- Broken bones or trauma
- Internal vessel injury
3. 🧬 Genetic factors
Some people inherit conditions that make clotting more likely:
- Factor V Leiden mutation
- Protein C or S deficiency
- Antithrombin deficiency
4. 💊 Medical conditions
Certain diseases increase risk:
- Cancer
- Heart disease
- Stroke history
- Autoimmune disorders
- Severe infections (including COVID-19 in some cases)
5. 🧍 Lifestyle factors
- Smoking 🚬 (damages blood vessels)
- Obesity
- Lack of physical activity
- Dehydration
6. 💊 Medications and hormones
Some medicines can increase clot risk:
- Birth control pills or hormone therapy
- Some cancer treatments
- Certain blood pressure or hormone drugs
7. 🧓 Age and health changes
- Risk increases with age (especially over 60)
- Vein problems like varicose veins can contribute
⚠️ Dangerous clot locations
- Deep veins (DVT) in legs → swelling, pain
- Lungs (pulmonary embolism) → chest pain, shortness of breath
- Brain (stroke) → weakness, speech problems
🧠 Simple summary
Blood clots are usually caused by a mix of:
- Slow blood flow
- Vessel damage
- Increased clotting tendency (genetics or illness)
🚨 When to seek urgent help
- Sudden chest pain or difficulty breathing
- Swollen, painful leg (especially one-sided)
- Sudden weakness, confusion, or speech trouble
