Can you donate blood with low blood pressure?
It depends on your reading on the day. Blood pressure is measured before every donation. If it is below the accepted range you will be deferred for that visit, not permanently.
Low blood pressure (hypotension) is checked at the mini-physical before each donation. It is not a permanent deferral. The test is your reading on the day.
Reference range
Blood centers generally accept a systolic (top) number from about 90 to 180 and a diastolic (bottom) number from about 50 to 100 mmHg. Exact limits can differ slightly by center.
If your reading is below the limit, the donation is postponed.
Why very low pressure is a concern
Giving blood temporarily lowers your blood volume. If you already run low, that raises the risk of:
- Fainting
- Strong dizziness and nausea
- A symptomatic drop in blood pressure after the draw
What to do if you run low
- Drink plenty of water before you go
- Eat a regular meal with some salt
- Rest for a few minutes before the measurement
- If it stays low, try another day
Dizziness when standing
If you often feel lightheaded when you stand up, say so. That pattern raises the risk of fainting and can justify postponing even when your resting reading is in range.
Medications
If you take medicine to raise blood pressure, check with the blood center.
This information is general and does not replace advice from a health professional. Your eligibility is always decided at the donor screening on the day of donation. Rules change, so confirm with the American Red Cross or the blood center where you plan to donate.