Most healthy adults can donate blood, but a surprisingly long list of conditions, medications, recent experiences, and even travel history can make you temporarily or permanently ineligible. Some disqualifications last just a few days, while others are lifelong. Here’s a clear breakdown of what keeps people from donating.
Basic Age, Weight, and Health Requirements
You must be at least 17 years old to donate blood in most states, though some allow 16-year-olds with parental consent. You also need to weigh at least 110 pounds. These thresholds exist because removing a pint of blood from someone too young or too small can cause a disproportionate drop in blood volume.
On the day of your donation, staff will check your vital signs. Your systolic blood pressure (the top number) must fall between 90 and 180, and your diastolic (bottom number) between 50 and 100. Your pulse needs to be regular and between 50 and 100 beats per minute. If your readings fall outside those ranges, you’ll be turned away that day, though you can try again another time.
You also need adequate iron levels in your blood. The minimum hemoglobin level is 13.0 g/dL for men and 12.5 g/dL for women, though women with levels as low as 12.0 g/dL may be accepted at some facilities under additional safety protocols. This is checked with a quick finger prick before every donation. Low iron is one of the most common reasons people get deferred on the spot, especially women who menstruate and frequent donors.
Health Conditions That Permanently Disqualify You
Certain diagnoses mean you can never donate blood. These permanent deferrals exist because the conditions either pose a risk to the recipient or cannot be reliably screened out of donated blood.
- HIV: A positive test at any point in your life permanently disqualifies you.
- Hepatitis B or C: A positive hepatitis test results in a permanent deferral.
- Certain blood cancers and malignancies: Leukemia, lymphoma, Hodgkin’s disease, multiple myeloma, myelodysplastic syndrome, and polycythemia vera all result in permanent disqualification.
- Malignant melanoma: Unlike many other skin cancers, melanoma permanently bars you from donating.
Other chronic conditions don’t always result in a permanent ban but may disqualify you depending on severity and treatment. If you have a condition like sickle cell disease, a bleeding disorder, or a history of organ transplant, you’ll need to discuss your specific situation with the blood center.
Medications That Create Waiting Periods
Most everyday medications, including common pain relievers, allergy pills, and blood pressure drugs, won’t prevent you from donating. But a handful of specific drugs require a waiting period after your last dose.
Isotretinoin (the active ingredient in acne medications like Accutane, Absorica, and Claravis) requires a one-month wait after your last dose. The same one-month deferral applies to finasteride, used for hair loss and enlarged prostate. Dutasteride, a similar drug, requires a six-month wait. These medications can cause birth defects, and the concern is that trace amounts in donated blood could reach a pregnant recipient.
Prescription blood thinners are a bigger issue. If you’re currently taking warfarin, heparin, or newer blood thinners like apixaban, rivaroxaban, or dabigatran, you cannot donate because your blood won’t clot normally. If your doctor takes you off warfarin, you need to wait 7 days. For the newer blood thinners, the wait is 2 days after your last dose.
Aspirin is fine for whole blood donation with no waiting period. But if you’re donating platelets specifically, you need to wait 2 full days after taking aspirin.
Infections and Feeling Sick
You need to be feeling well on the day you donate. A cold, flu, stomach bug, or any active infection means you should reschedule. If you’re currently taking antibiotics for an infection, you’re not eligible until you’ve finished the course and the infection has cleared.
For COVID-19, you need to wait at least 10 days after your symptoms have resolved before donating. The key word is resolved: the clock starts when you feel better, not when you first got sick.
Travel to Malaria-Risk Areas
Malaria is one of the trickiest infections to screen for in blood donations because it can persist in the body without symptoms. The rules depend on how long you were in an affected area.
If you traveled to a region where malaria is present, you must wait 3 months after returning before donating. If you lived in a malaria-endemic area (rather than just visiting), the wait extends to 3 years. And if you were actually diagnosed with malaria, you’re deferred for 3 years after completing treatment, provided you’ve had no recurring symptoms during that time.
Tattoos, Piercings, and Recent Procedures
Getting a tattoo doesn’t necessarily prevent you from donating. In most states, tattoos applied at state-regulated facilities using sterile, single-use needles and fresh ink are accepted with no waiting period. However, if your tattoo was done in a state that doesn’t regulate tattoo shops, you’ll need to wait 3 months.
The same logic applies to piercings. If single-use, disposable equipment was used, you’re fine. If a reusable piercing gun was involved, or if there’s any doubt about the equipment, the wait is 3 months.
Pregnancy and Breastfeeding
You cannot donate blood while pregnant. After giving birth, the World Health Organization recommends a deferral period of at least 9 months, and you should also wait until at least 3 months after your baby has been significantly weaned, meaning the baby is getting most nutrition from solid food or formula rather than breast milk. This protects the mother’s iron stores and blood volume during a period of high physical demand.
Sexual Activity and HIV Risk Screening
Blood donation screening in the U.S. underwent a major change in 2023. The FDA eliminated the long-standing policy that specifically deferred men who have sex with men. In its place, every donor now answers the same set of individual risk-based questions regardless of sex or sexual orientation.
The current screening focuses on recent sexual behavior that carries higher HIV transmission risk. If you’ve had a new sexual partner in the past 3 months and also had anal sex during that period, you’ll be deferred for 3 months from your most recent sexual contact. The same 3-month deferral applies if you’ve had more than one sexual partner in the past 3 months and had anal sex during that window. These questions apply equally to all donors.
Common Temporary Deferrals at a Glance
- Cold or flu: Wait until symptoms resolve.
- Antibiotics: Wait until the course is finished and the infection is cleared.
- COVID-19: 10 days after symptoms resolve.
- Tattoo or piercing (unregulated): 3 months.
- Travel to a malaria-risk area: 3 months.
- Isotretinoin or finasteride: 1 month after last dose.
- Dutasteride: 6 months after last dose.
- Blood thinners (after discontinuation): 2 to 7 days depending on the drug.
- New sexual partner plus anal sex: 3 months.
- After childbirth: At least 9 months, plus 3 months after significant weaning.
If you’ve been deferred in the past, it’s worth checking again. Policies change, and many deferrals are temporary. Blood centers would rather help you figure out when you can donate than simply turn you away.