Most healthy adults aged 17 or older who weigh at least 110 pounds can donate blood. But a surprisingly long list of factors, from medications to travel history to time spent in Europe decades ago, can delay or permanently prevent you from donating. Here’s a full breakdown of what qualifies you and what doesn’t.
Basic Age and Weight Requirements
You need to be at least 17 years old in most states, though 16-year-olds can donate with parental consent. The minimum weight is 110 pounds for whole blood donation, and height-to-weight requirements may be stricter for other donation types like double red cells or platelets.
Before every donation, your hemoglobin (the oxygen-carrying protein in red blood cells) is tested with a quick finger prick. Women need a level of at least 12.5 g/dL, and men need at least 12.5 g/dL as well. Low iron is one of the most common reasons people get turned away at the door, and it’s especially common in women of reproductive age. If you’ve been deferred for low hemoglobin before, eating iron-rich foods and spacing your donations further apart can help.
Conditions That Permanently Disqualify You
Some medical histories result in a lifetime ban from donating. You can never donate if you:
- Have tested positive for HIV or have been diagnosed with AIDS, even with treatment
- Have had hepatitis B or hepatitis C
- Have been diagnosed with leukemia or lymphoma
- Have been diagnosed with variant Creutzfeldt-Jakob disease (vCJD) or any other form of CJD
- Are currently taking any medication to treat HIV (antiretroviral therapy)
These permanent deferrals exist because the infections or conditions involved pose a risk to blood recipients that screening alone can’t fully eliminate.
The 2023 Change to Sexual History Screening
For decades, men who had sex with men faced blanket deferrals, first permanently, then for 12 months, then 3 months. In 2023, the FDA overhauled this approach entirely. The agency now recommends that all donors, regardless of sex or gender, answer the same individual risk-based screening questions about HIV risk.
The updated guidance eliminated questions specific to men who have sex with men. Instead, screening focuses on specific behaviors that carry higher HIV risk, like having a new sexual partner and engaging in anal sex, which carries a significantly higher transmission risk than other sexual contact. Anyone taking oral or injectable medication to prevent HIV (PrEP or PEP) faces a two-year deferral from their last dose, and anyone on HIV treatment medications is permanently deferred.
Medications That Require a Waiting Period
Many common medications won’t affect your eligibility at all. Aspirin, most antibiotics (once you’ve finished them and feel well), birth control, and blood pressure medications are generally fine. But several drug categories require specific waiting periods:
- Blood thinners: Most require a 7-day wait, including common prescriptions for preventing blood clots and strokes.
- Antiplatelet drugs: Wait times range from 2 days to 1 month depending on the specific medication. If you take these for stroke or heart attack prevention, ask at your donation center.
- Isotretinoin (severe acne treatment): 1 month after your last dose.
- Finasteride (hair loss or prostate medication): 6 months.
- Dutasteride (prostate medication): 6 months.
- HIV prevention drugs (PrEP/PEP): 2 years after your last dose, whether oral or injectable.
Some medications result in even longer deferrals. Certain drugs for psoriasis and rheumatoid arthritis require a 3-year wait. If you’re unsure about a specific medication, the donation center will check it against their deferral list before you give blood.
Travel to Malaria-Risk Areas
If you’ve traveled to an area where malaria is present, you’ll need to wait 3 months after returning before you can donate. If you previously lived in a malaria-endemic area, the wait extends to 3 years. And if you were actually diagnosed with and treated for malaria, you must wait 3 years after treatment and remain symptom-free during that entire period.
Time Spent in the UK or Europe
Concerns about mad cow disease (vCJD) still affect donation eligibility today. The rules are specific and based on where and when you lived:
- 3 or more cumulative months in the UK from 1980 through 1996: permanently deferred
- 6 or more cumulative months on US military bases in Northern Europe (Germany, Belgium, Netherlands) from 1980 through 1990: permanently deferred
- 6 or more cumulative months on US military bases elsewhere in Europe (Greece, Turkey, Spain, Portugal, Italy) from 1980 through 1996: permanently deferred
- 5 or more cumulative years anywhere in Europe from 1980 to the present: permanently deferred
- Received a blood transfusion in the UK or France from 1980 to the present: permanently deferred
These deferrals affect a significant number of otherwise healthy donors, particularly military families and people who studied or worked abroad. Because vCJD has no reliable blood screening test, the deferrals remain in place despite the disease being extremely rare.
Tattoos and Piercings
In most states, a tattoo won’t delay your donation at all, as long as it was done at a state-regulated facility using sterile needles and ink that wasn’t reused. The same applies to cosmetic tattoos and microblading. However, if you got your tattoo in a state that doesn’t regulate tattoo facilities, you’ll need to wait 3 months.
Piercings follow similar logic. If single-use, disposable equipment was used (both the piercing instrument and the earring cassette), you’re eligible right away. If a reusable gun or instrument was involved, or if there’s any uncertainty about whether the equipment was disposable, the wait is 3 months. These waiting periods exist because hepatitis can be transmitted through contaminated needles and is easily passed to blood recipients through transfusion.
Pregnancy and Breastfeeding
You cannot donate blood while pregnant. After giving birth, the World Health Organization recommends waiting at least 9 months, and then an additional 3 months after your baby is significantly weaned, meaning the baby is getting most nutrition from solids or formula rather than breastfeeding. This extended timeline allows your body to fully recover its blood volume and iron stores.
How Often You Can Donate
Even if you’re fully eligible, there are limits on how frequently you can give. For whole blood, you must wait at least 56 days (8 weeks) between donations. Double red cell donations require 112 days (16 weeks) between sessions because they take twice the red blood cells in a single visit. Platelet donations have the shortest interval at just 7 days apart, since your body replenishes platelets much faster than red blood cells.
These intervals protect your own health. Donating too frequently can deplete your iron stores over time, which is why many donation centers now offer iron supplements or recommend them to frequent donors.