To donate blood in the United States, you generally need to be at least 17 years old (16 with parental consent), weigh at least 110 pounds, and be in good health. Beyond those basics, eligibility depends on your hemoglobin levels, medications, recent travel, and other factors that blood centers screen for at every visit. Here’s what you need to know before you schedule an appointment.
Age, Weight, and Hemoglobin Requirements
The core requirements are straightforward: you must be at least 17 in most states (16 with a parent’s written consent) and weigh a minimum of 110 pounds. Before each donation, staff will check your hemoglobin, the protein in red blood cells that carries oxygen. Men need a level of at least 13.0 g/dL, and women need at least 12.5 g/dL. Some blood centers can accept women with hemoglobin as low as 12.0 g/dL if they follow additional safety protocols approved by the FDA.
If your hemoglobin comes back too low, you’ll be turned away that day but can try again later. Low iron is the most common reason otherwise healthy donors get deferred, especially women who menstruate. Eating iron-rich foods in the weeks leading up to your appointment can help.
How Often You Can Donate
The waiting period between donations depends on what you’re giving:
- Whole blood: every 12 weeks (about 3 months)
- Platelets or plasma (apheresis): every 4 weeks
- Double red cells (Power Red): every 16 weeks
Power Red donations collect twice the red blood cells of a standard donation using a specialized machine, which is why they require a longer gap between visits. They also have stricter size requirements: male donors must be at least 5’1″ and 130 pounds, while female donors must be at least 5’3″, 150 pounds, and 19 years old.
Medications That Affect Eligibility
Most medications, including common ones like blood pressure pills, antidepressants, and birth control, do not disqualify you. The ones that do typically require a temporary waiting period rather than a permanent ban. A few of the most common:
- Blood thinners: Most require a 2-day wait after your last dose. Warfarin and heparin require 7 days.
- Isotretinoin (acne treatment): 1 month after your last dose.
- Finasteride (hair loss or prostate medication): 6 months.
- Oral HIV prevention (PrEP/PEP): 3 months after stopping. Injectable forms like cabotegravir require a 2-year wait.
- HIV treatment (antiretroviral therapy): permanent deferral.
- Experimental medications: 12 months.
Some medications used for conditions like psoriasis, multiple sclerosis, or rheumatoid arthritis carry deferral periods of 2 to 3 years. If you’re on a medication you’re unsure about, calling the blood center ahead of time saves you a wasted trip.
Tattoos and Piercings
A recent tattoo does not automatically disqualify you. In most states, if your tattoo was done at a state-regulated facility using sterile, single-use needles and ink, you can donate with no waiting period. The same applies to cosmetic tattoos and microblading. If the facility was not state-regulated, or you’re unsure, you’ll need to wait 3 months.
Piercings follow similar logic. If the piercing was done with single-use, disposable equipment, you’re eligible right away. If a reusable piercing gun was used, or there’s any doubt about the instruments, the wait is 3 months.
Travel Restrictions
Travel to certain regions can trigger temporary deferrals because of disease risk. Malaria-endemic areas are the most common concern, and deferral periods vary depending on where you went and how long you stayed. Blood centers maintain updated lists of affected countries, so it’s worth checking before your appointment if you’ve traveled internationally in the past year.
Zika virus was once a major screening concern, but the FDA removed the requirement for Zika testing of blood donations in May 2021 due to the sharp global decline in cases. If you’ve been diagnosed with Zika in the last 4 months, however, you should still notify the blood center and hold off on donating.
Individual Risk Assessment for HIV
The FDA updated its approach to HIV-related donor screening, replacing the older policy that deferred men who have sex with men for a set time period. The current guidance uses individual risk-based questions for all donors regardless of sexual orientation. The screening now focuses on specific recent behaviors, such as having a new sexual partner or multiple partners, rather than categorically excluding people based on identity. This change brought U.S. policy in line with the science showing that individual risk assessment is effective at protecting the blood supply.
What to Eat and Drink Before Donating
Donating removes red blood cells, and your body needs about eight weeks to fully replace the iron lost in a single whole blood donation. Eating iron-rich foods in the days before your appointment helps protect your stores. Good options include red meat, eggs, poultry, fish, and leafy greens like spinach. Pairing those with vitamin C sources (citrus fruit, pineapple, mangoes, Brussels sprouts) helps your body absorb the iron more efficiently.
Hydration matters too. Drink plenty of water before your appointment. Being well-hydrated makes your veins easier to find and reduces the chance of feeling lightheaded afterward.
After You Donate
The donation itself takes about 10 minutes for whole blood. Afterward, you’ll rest briefly and have a snack. For the rest of that day, skip heavy lifting, vigorous exercise, and any work at heights. Athletes should wait at least 12 hours before returning to strenuous training.
Over the next 24 hours, drink an extra four glasses of water (8 ounces each) and avoid alcohol, which can dehydrate you and amplify dizziness. Most people feel completely normal the next day, though some notice mild fatigue for a day or two, especially if their iron was on the lower side going in.