What Precaution To Be Taken Before Donating Blood ?

Posted on Tue, 21 Jul 2020

Medically reviewed by Ask A Doctor - 24x7 Medical Review Team

Tue, 21 Jul 2020 Answered on

Tue, 12 Aug 2025 Last reviewed on

Question : Hello, the last time I donated blood, I ate a low fat breakfast prior to. All went well. I left the donation center, was eating some jelly beans, and did a little grocery shopping. As I stepped in the apt, I began to feel faint. I then began to throw up. I am non insulin dependent diabetic but had not taken metformin prior to donation. Never had after effects from donation until now. I’m scheduled to donate again but feeling nervous about it.

Answered by Dr. Panagiotis Zografakis (6 hours later)

Brief Answer:
perhaps the effects of lower blood volume...

Detailed Answer:
Hello,

the donation itself does not have any side effects except the reduction of blood volume. In most individuals, this is not too much to bear with and it usually only causes minimal -if it does at all- symptoms. Perhaps your age and your history of diabetes have made your arteries less compliant which may translate into an exaggerated blood pressure reduction after losing some blood volume. The most common first manifestation of this disorder is orthostatic (postural) hypotension which may present as faintness, nausea, vomiting, etc, and - if the individual does not lie down immediately - even syncope.

The body usually corrects the low blood volume soon enough though. Prolonged symptoms would warrant a careful assessment of potential cardiovascular (ischemic) complications.

I hope I've answered your question. Please let me know if you need further assistance.

Kind Regards,
Dr. Panagiotis Zografakis,
Internal Medicine Specialist

Above answer was peer-reviewed by : Dr. Chakravarthy Mazumdar