LivingWhen can I donate blood?

When can I donate blood?

Blood donations are essential daily for carrying out multiple treatments and interventions, but what is blood? what is it for?

The blood circulates through the arteries and veins, has a bright red color and represents 1/13 of the total weight of the human body. We would say that if you weigh 65 kilos, you would have 5 liters of blood.

What do we find in our blood?

Blood is made up of a liquid called plasma that represents 55% in which we find cells such as red blood cells (43), white blood cells and platelets (2%).

They are made in the bone marrow specifically in the spongy tissue found inside the bones.

the plasma

It is a liquid composed of mineral salts, water, mineral salts and other substances necessary for the body. In the plasma we find the blood cells.

Red blood cells or red blood cells

They are the most numerous blood cells , they contain hemoglobin that is responsible for their characteristic red color. They are formed in the bone marrow and carry oxygen from the lungs to the tissues. They have a half-life of four months.

The excess of red blood cells is called erythrocytosis . Red blood cell deficiency is called anemia .

white blood cells

Unlike red blood cells, they are the least numerous but are responsible for protecting the body from different microbes.

They have a half-life of less than 24 hours and a person has between 4,000 and 10,000 leukocytes per cubic millimeter.


Platelets have the function of joining together to intervene when blood vessels break. This union forms a clot that stops the bleeding.

They have a half-life between 5 and 7 days outside our body and we have between 150,000 and 400,000 per cubic millimeter.

What do I need to know if I want to donate blood?

You must be over 18 years old and under 65 if you have never donated, weigh more than 50 kg and be healthy and make sure you come to donate without fasting.

Blood donation is a safe act . For this reason, before donating you will undergo a short medical interview in which your blood pressure will be assessed and your hemoglobin (red blood cell) levels will be checked.

Sometimes it is not possible to donate when we are taking medication, when we have an illness, we have traveled or we have had risky practices, but they have to assess this with you in the interview.

If you’ve gotten a tattoo, it takes four months to donate blood again

The moment of donation is short, around 5 or 7 minutes, it is not painful , it feels the same as in a blood test and you have to be relaxed.

The amount of blood that is going to be extracted from you is very small compared to what you have in your body, so you do not have to have any subsequent discomfort.

Blood donation is a simple and safe process that saves lives. Specifically, the blood is separated into its 3 components that we have mentioned above, red blood cells, platelets and plasma.

The separation of the blood into its components is used by three different nurses, so we can say that a donation will help 3 people.

Covid and blood donation is it safe?

We start from the basis that the requirements to go to donate is to be between 18 and 65 years old, weigh more than 50 kilos and be in good health. This can generate doubts with the subject of Covid 19.

Although the regulations could change, the criteria to donate if you have been infected with covid are the following:

  1. Positive diagnosis for COVID-19 and no symptoms, the period to donate will be 7 days.
  2. For people with a positive diagnosis with mild or moderate symptoms, the exclusion period will be 7 days from the disappearance of symptoms.
  3. For people who have severe symptoms or even who have been hospitalized, the exclusion period is 14 days from the end of the symptoms and/or from discharge.

Another issue that can generate doubts is the issue of vaccination, donation is not contraindicated but you must wait 48 hours to be able to donate.

Blood donation is an altruistic gesture and an irreplaceable part of saving lives. Every time you donate, you save three lives. Do not hesitate to go to your nearest donation center and find out about it.

Bibliographic references

Madrid’s community. 2022. Blood donation.

Red Cross. 2022. Blood donation


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