1 Blood donation takes four steps: medical history, quick physical, donation, and snacks. 2  The actual blood donation usually takes less than 10 minutes. 3  The entire process, from when you sign in to the time you leave, takes about 45 minutes. 4  Giving blood will not decrease your strength.
Hives are red and sometimes itchy bumps on your skin. An allergic reaction to a drug or food usually causes them. Allergic reactions cause your body to release chemicals that can make your skin swell up in hives. People who have other allergies are more likely to get hives than other people. Other causes include infections and stress.
Hives, also known as urticaria, are an outbreak of swollen, pale red bumps, patches, or welts on the skin that appear suddenly -- either as a result of allergies, or for other reasons.