To donate blood in the United States, you must be at least 17 years old (or 16 with parental consent), weigh at least 110 pounds, and be in generally good health. Those are the baseline requirements, but the full picture includes hemoglobin levels, medications, recent travel, tattoos, and how long you need to wait between donations. Here’s what you actually need to know before scheduling an appointment.
Age, Weight, and Basic Health
The minimum age is 17 in most states, though 16-year-olds can donate with a parent’s written consent. There is no strict upper age limit at most blood centers as long as you meet the other criteria. You need to weigh at least 110 pounds because smaller bodies have less total blood volume, and losing a pint could cause complications like dizziness or fainting.
You also need to be feeling well on the day of your donation. Your blood pressure and body temperature are checked at the appointment and must fall within acceptable ranges. If you’re running a fever or feeling under the weather, you’ll be asked to come back another time.
Hemoglobin Levels
Before every donation, a quick finger-prick test measures your hemoglobin, the protein in red blood cells that carries oxygen. The FDA requires a minimum of 13.0 g/dL for men and 12.5 g/dL for women. If you fall below that cutoff, you’ll be temporarily deferred. This is one of the most common reasons people get turned away, especially women and frequent donors.
Low hemoglobin often reflects low iron stores. If you donate regularly, the industry group AABB recommends taking a low-dose iron supplement (at least 18 mg per day) for 60 days after a whole blood donation. Some countries go further: Denmark screens donors’ iron stores on the first visit and periodically afterward, deferring anyone whose levels are too low. In the U.S., iron monitoring is encouraged but not universally required, so it’s worth paying attention to your own diet and energy levels if you donate frequently.
Medications That Delay Donation
Most common medications, including those for high blood pressure, cholesterol, and thyroid conditions, do not disqualify you. But certain drugs require a waiting period because they can harm a blood recipient or indicate a condition that makes donation unsafe.
- Isotretinoin (acne medication): 1 month after your last dose
- Blood thinners like warfarin, apixaban, or rivaroxaban: 7 days
- Antiplatelet drugs like clopidogrel: 14 days
- Finasteride (used for hair loss or prostate symptoms): 6 months
- Oral HIV prevention drugs (PrEP/PEP): 3 months
- Injectable HIV prevention: 2 years
- HIV treatment medications: permanent deferral
Antibiotics are a special case. If you’re taking them for an active infection, you can donate 24 hours after your last dose as long as you have no remaining signs of infection. Antibiotics taken for acne don’t require any waiting period at all.
Colds, Flu, and Recent Illness
If you’ve had a cold or the flu, you need to be completely symptom-free for 48 hours before donating. That means no lingering cough, congestion, or fever. The concern isn’t that your cold virus would infect the recipient through the blood supply. It’s that donating while your body is still fighting something off can make you feel significantly worse.
Tattoos and Piercings
A tattoo does not automatically disqualify you. In most states, if you got your tattoo at a state-regulated facility that uses sterile needles and single-use ink, you can donate with no waiting period. If the facility wasn’t regulated by the state, you’ll need to wait three months.
Piercings follow a similar rule. If the piercing was done with single-use, disposable equipment, you’re eligible right away. If a reusable instrument was involved, or if you’re not sure, the wait is three months.
Travel to Malaria-Risk Areas
If you’ve traveled to an area where malaria is common, you’ll need to wait three months after returning before you can donate. This is a recent change; the deferral period used to be a full year. If you previously lived in a malaria-endemic area, the wait is three years. Anyone who has been diagnosed with and treated for malaria must also wait three years after treatment, provided they’ve had no recurring symptoms.
HIV Risk Screening
The FDA updated its blood donor screening guidelines in 2023, replacing the older policy that deferred men who have sex with men as a blanket category. The current approach uses individual risk-based questions for all donors, regardless of gender or sexual orientation. These questions focus on specific recent behaviors, like having a new sexual partner or multiple partners in the past three months, rather than on identity. This change brought U.S. policy in line with the scientific evidence on HIV transmission risk and modern blood testing capabilities.
How Often You Can Donate
The required gap between donations depends on what you’re giving. For whole blood, you need to wait at least eight weeks (56 days) between donations in the U.S. Double red cell donations, which collect twice the red cells in a single session, require a longer gap of about 16 weeks. If you donate platelets or plasma through apheresis, you can return as soon as two weeks later, since those components regenerate much faster than red blood cells.
Frequent whole blood donors, particularly women before menopause, are at higher risk for iron depletion. Eating iron-rich foods like beans, lentils, leafy greens, and nuts between donations helps, and pairing them with vitamin C (citrus, berries) improves absorption.
What to Bring and How to Prepare
You’ll need a valid photo ID, such as a driver’s license or passport. Specific requirements vary by donation center, but government-issued ID is the standard.
In the hours before your appointment, drink at least 16 ounces of water and avoid alcohol and caffeine, both of which dehydrate you. Eat a meal beforehand, but skip high-fat foods like fried items or ice cream, since fat in your blood can interfere with testing. Focus on iron-rich foods in the days leading up to your donation to give your hemoglobin the best chance of clearing the screening.
The actual donation takes about 10 minutes for whole blood, with the entire visit, including registration, screening, and a short recovery period, lasting roughly an hour.