National Blood Donor Month: Know how donating blood affects your body, precautions to take

Most people are worried about donating blood as they feel it will lead to significant weakness and might cause problems to them. Hence, it is important to understand what happens to your body after donating blood.

Once a person is evaluated for blood donation and considered fit, around one pint of blood (around 450 ml) is removed from the donor’s body in a sitting. It is important to understand what happens inside the body after donating blood. Normally our body has around 4 to 5 litres of blood. Once the desired amount of blood is removed, there is an immediate decrease in blood volume which causes dizziness in some patients. Our body adjusts the blood volume loss by fluid shift and within a few minutes the desired volume is pushed inside the circulation. Adequate hydration is therefore an important thing to remember before and after blood donation.

The rest of components in blood are replaced within a few days inside the body. With the iron stores in the body, gradually haemoglobin is restored. A healthy person who is considered fit for blood donation usually has enough iron stores to replace the loss. Since overall haemoglobin levels are good in donors, most patients do not experience any symptoms related to slightly low haemoglobin.

The most common symptoms after the blood donation are light headedness and dizziness which occurs in around 2% of people. This usually happens within a few minutes of donation and that is why it is a common practice to have a bed rest of 15 minutes after blood donation. To avoid this, it is recommended to have adequate hydration before and after blood donation.

It is a general recommendation to avoid strenuous physical activities and heavy weightlifting for 24 hours after the blood donation. As per a study from the Netherlands, where around 3000 donors were followed up for one week after donating blood. The symptoms commonly encountered were lightheadedness, dizziness, fatigue, headache. On follow up, in most patients the symptoms lasted less than 24 hours after blood donation. In 1% of patients few mild symptoms lasted for around 3 days.

Based on this, after one day of blood donation, one can easily start workouts again. It’s recommended to start gradually as some people might have residual fatigue for two to three days. In our clinical experience, most patients resume their daily activities from the next day of blood transfusion including routine exercise and have no symptoms.

To summarise, one should not be worried about weakness or fatigue after blood donation. Every person is checked for fitness before donating blood including their haemoglobin levels.  

The author is Consultant Physician & Diabetologist, MBBS, DNB – General Medicine, Fellowship -DM- RCP-UK, Jaslok Hospital & Research Centre, Mumbai.

(Disclaimer: The views expressed above are the author's own and do not reflect those of DNA.)