Most people will feel okay after the donation. Some donors might experience slight giddiness. For all blood donors, the nurse will ask them to rest on the donation bench for 10 mins after their donation. 

If you feel slightly giddy after the donation, continue to rest on the donation bench after the 10 mins or at the refreshment area. Only leave when you feel ok. It is not necessary to eat more after the blood donation to compensate. Blood volume can be replaced just by drinking plenty of fluids. 

You should avoid strenuous exercise after donating. Your athletic performance might be slightly lower for the next 3 days. 

Here are some tips on post-donation care you can read. 

Please eat a light meal, drink plenty of water and have a good night's rest before donation. No fasting is needed before blood donation. Should you feel unwell on the day of donation, take a rest and consider postponing the donation until you feel better. Avoid drinking tea or coffee and consuming calcium-rich foods (milk, cheese, yogurt) with iron-rich meals or iron supplements. Tannins in tea, caffeine in coffee and calcium reduce iron absorption. Have your coffee or tea after your meals. 

Each blood donation usually takes 45-60 minutes and up to 90 minutes for an apheresis donation.  

Donating blood is a simple process. You can prepare for your donation by checking your eligibility and making an appointment. On the day of donation, you’ll need to register at the Bloodbank and complete a detailed health assessment before donating.