There are many medical situations in which blood transfusion is the only needed therapeutic measure to save lives (as in cases of severe bleeding or internal hemorrhage). So blood donation is very important to save lives and to help them to survive.
On the other side, donating blood involves many health benefits for the donor too; they include the following:

1. It improves emotional and psychological states by providing the sense of satisfaction and self-esteem, because of the donor is doing a charitable act that saves lives.
2. Blood donation should be preceded with a series of tests to check the donor's blood to ensure that it's clinically free from any pathology. Also, the donor's vital data are checked. So, we can say that regular blood donation resembles a check-up for the general health condition of the donor.
3. Medical studies showed that regular blood donation reduces the risk of cardiac problems, strokes and formation of blood clots. This is because blood donation stimulates the body to produce new and more youthful blood cells.

To donate blood, the following criteria must be met:

• The age of donor should be more than 18 years old and less than 50 years old. Also, the donor should be physically and psychologically fit for donation.
• The vital data (blood pressure, pulse, temperature and respiratory rate) of blood donor should be within normal ratios.
• Blood donor should wait at least 3 months for another donation.
• Blood donor should be free of anemia, blood coagulopathy as well as chronic diseases, such as; hypertension, diabetes, renal failure… etc.

On the same context, blood donation is contraindicated in the following conditions:

• Pregnancy or lactation. 
• Cardiac health problems, such as; hypertension and cardiomyopathy.
• Renal or hepatic failure.
• Diabetes mellitus.
• Chronic respiratory problems, such as bronchial asthma or COPD.
• Malnutrition disorders.
• Autoimmune diseases.
• Thyroid dysfunction.
• Abnormal coagulation profile.
• Epilepsy. 
• Viral hepatitis.