Can you donate blood to anyone? Here's what you need to know

Every two seconds, someone in the world needs a blood transfusion.

Whether it's a cancer patient, a trauma victim, a sickle cell patient, or someone undergoing surgery, donated blood is often the difference between life and death. Yet, less than 5% of eligible donors actually give blood regularly.

One of the most important aspects of blood donation is blood type compatibility, knowing who can donate to whom. Understanding this can help potential donors realise how vital their contribution can be.

Blood types are determined by two key factors: the ABO group and the Rh factor.

• ABO group: You can have blood type A, B, AB, or O.

• Rh factor: You’re either Rh-positive (+) or Rh-negative (-), depending on the presence or absence of a specific protein on your red blood cells.

The combination of these creates eight main blood types: A+, A-, B+, B-, AB+, AB-, O+, and O-.

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Each blood type has its own set of donation rules based on compatibility. Receiving the wrong blood type can trigger an immune response, which can be life-threatening. Here's how compatibility works:

If you have O negative blood, your red cells can be given to anyone, regardless of their blood type. This is why O-blood is always in high demand, especially in emergencies when there's no time to test a patient's blood type. However, O- individuals can only receive O- blood themselves.

At the other end of the spectrum, AB-positive individuals can receive blood from any other type. That makes them universal recipients, though they can only donate to others with AB+ blood.

People with O-positive blood can donate to A+, B+, AB+, and O+, making them one of the most versatile and needed blood types. However, they can only receive from O+ or O-.

• If you’re A positive, you can donate to A+ and AB+, and receive from A+, A-, O+, and O-.

• If you’re A negative, you can donate to A-, A+, AB-, and AB+, and receive from A- and O-.

• A person with B positive blood can donate to B+ and AB+, and receive from B+, B-, O+, and O-.

• B negative donors can give to B-, B+, AB-, and AB+, and receive from B- and O-.

• AB positive is the most accepting blood type, capable of receiving red blood cells from all other blood types. However, they can only donate to other AB+ individuals.

• AB negative can receive from AB-, A-, B-, and O-, and donate to AB- and AB+.

Compatibility ensures the donor’s red blood cells can flow through the recipient’s bloodstream without triggering an immune attack. If incompatible blood is transfused, the immune system may destroy the new red blood cells, which can lead to serious or fatal complications.

This is why hospitals keep a stock of O- blood on hand. In trauma or emergency situations where there's no time to confirm the patient’s blood type, O- is used as a safe option.

Generally, if you're healthy, at least 16 years old (with parental consent), and weigh over 110 pounds, you can donate. Blood donation is safe, and only one pint is drawn at a time; your body can replenish the lost plasma within 24 hours and red cells within five weeks. You can typically donate again after eight weeks.

Each donation can save up to three lives, since donated blood is usually separated into components: red cells, plasma, and platelets.

Before you donate:

• Eat a healthy, iron-rich meal.

• Avoid fatty or fried foods.

• Stay hydrated.

After donating, eat well, drink fluids, and avoid heavy lifting for at least 12 hours.

Knowing your blood type isn’t just about curiosity; it could be the key to saving someone’s life. Whether you're a universal donor or only compatible with a select few, your contribution matters.

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