You should not give blood if you have certain infections, are taking specific medications, weigh under 110 pounds, or feel unwell on the day of your donation. Some conditions disqualify you permanently, while others require a waiting period of days to years. Here’s a full breakdown of what can make you ineligible.
Conditions That Permanently Disqualify You
A few medical conditions will prevent you from ever donating blood. HIV infection is the most well-known: even if you’re on treatment and the virus is undetectable, antiretroviral drugs don’t fully eliminate HIV from the body, and donated blood could still transmit the virus. A positive HIV test result at any point in your life is a permanent disqualification.
Creutzfeldt-Jakob disease (the human form of mad cow disease) also results in a permanent deferral. If you’ve ever received a dura mater graft, which is a transplant of the tissue covering the brain from a cadaver, you’re permanently ineligible because of the risk of carrying this disease. Bleeding disorders like hemophilia lead to indefinite deferral as well, primarily to protect the donor’s own safety rather than the recipient’s.
Cancer policies vary by blood center and depend on the type and how long ago you were treated. Each facility sets its own rules based on medical judgment, so if you have a history of cancer, it’s worth calling ahead.
Medications That Require a Waiting Period
Several common medications temporarily disqualify you from donating. Isotretinoin (sold under brand names like Accutane, Claravis, and Zenatane), used for severe acne, requires a one-month wait after your last dose. Finasteride (Proscar), used for prostate conditions and hair loss, requires a six-month wait. These drugs can cause birth defects, and blood containing them could potentially reach a pregnant recipient.
Blood thinners have shorter waiting periods. Rivaroxaban (Xarelto), for example, requires a seven-day wait. The concern isn’t the recipient’s safety so much as yours: donating while on anticoagulants can cause excessive bleeding at the needle site.
HIV prevention medications also carry deferrals. If you’ve taken oral PrEP, you need to wait at least three months after your last dose. Long-acting injectable PrEP requires a two-year wait. These drugs can mask an early HIV infection, making it harder for screening tests to detect the virus in donated blood.
Being Sick or on Antibiotics
You can only donate if you have no symptoms of a cold, flu, or fever on the day of your appointment. Even mild symptoms like a runny nose or sore throat will get you turned away. If you’re taking antibiotics for an active infection, you’ll need to finish the entire course before you’re eligible. There’s no set number of days to wait after finishing antibiotics, but the infection itself needs to be fully resolved.
Low Iron and Hemoglobin Levels
Low hemoglobin is the single most common reason people get turned away at a blood drive. In one large study of deferred donors, it accounted for over a third of all temporary deferrals. Women are affected more often than men, largely because of menstruation and the iron it depletes.
Federal regulations set the minimum hemoglobin at 12.5 g/dL for women and 13.0 g/dL for men. Your hemoglobin is checked with a quick finger prick before every donation. If you’re below the threshold, you’ll be asked to come back another time. Eating iron-rich foods like red meat, spinach, and fortified cereals in the weeks before donating can help. If you’re repeatedly deferred for low hemoglobin, it’s worth having your iron stores checked, since hemoglobin can look normal even when your body’s iron reserves are running low.
Weight and Physical Requirements
You must weigh at least 110 pounds (50 kilograms) to donate. This threshold exists because the standard blood collection volume is calibrated for that minimum body weight. Donating at a lower weight increases the risk of feeling faint or having a serious reaction. There is no upper weight limit.
Tattoos and Piercings
Getting a tattoo, permanent makeup, or microblading doesn’t automatically disqualify you, but it depends on where the work was done. If the shop is regulated by the state and used sterile needles and single-use ink, you can donate with no waiting period. However, several states don’t regulate tattoo facilities, including Connecticut, Georgia, Idaho, Maryland, Massachusetts, New Hampshire, New York, Pennsylvania, Utah, and Wyoming, along with Washington, D.C. If your tattoo was done in one of those places, you’ll need to wait three months.
The same logic applies to body piercings. If single-use equipment was used (including chain stores like Claire’s), you’re eligible immediately. If not, it’s a three-month wait.
Travel to Malaria-Risk Areas
If you’ve traveled to a region where malaria is present, you cannot donate for three months after returning. If you previously lived in a malaria-endemic area, the wait extends to three years. And if you were actually diagnosed with malaria, you must wait three years after treatment and remain symptom-free throughout that period. These timelines were recently shortened from what they used to be (previously one year for travelers), reflecting better screening tools.
Time Spent in the UK During the Mad Cow Era
The FDA imposed a ban on blood donations from anyone who spent more than six cumulative months in Britain between 1980 and 1996, due to the risk of variant Creutzfeldt-Jakob disease (the human form of mad cow disease). This applies regardless of nationality. If you made multiple shorter trips during that window, you need to add them up. This deferral remains in effect and is one of the few travel-related restrictions that doesn’t expire.
Dental Work
Routine dental work like fillings or a scale and polish only requires a 24-hour wait. More invasive procedures, including root canals, tooth extractions, dental implants, and crowns, require a seven-day deferral. The concern is that bacteria entering the bloodstream during dental procedures could contaminate donated blood.
Pregnancy and Breastfeeding
You cannot donate blood during pregnancy or for six months after delivery. This applies equally after a termination of pregnancy. If you’re breastfeeding, you’re also deferred for the duration. Pregnancy and nursing place significant demands on your blood volume and iron stores, so the deferral is primarily about protecting your health.
High or Low Blood Pressure
Blood pressure is checked before every donation, and readings outside the acceptable range will get you deferred. Abnormal blood pressure is the second most common reason for temporary deferral, accounting for roughly a quarter of all same-day deferrals in large studies. If your blood pressure tends to run high, avoid caffeine and try to relax before your appointment. If it’s consistently out of range, that’s worth discussing with a doctor regardless of your plans to donate.