To donate whole blood in the United States, you generally need to be at least 17 years old (or 16 with parental consent), weigh at least 110 pounds, and be in good health on the day of your donation. Beyond those basics, the screening process checks your vital signs, asks about medications and travel history, and tests a small blood sample before you’re cleared to give.
Age, Weight, and General Health
The minimum age is 17 in most states, though 16-year-olds can donate with a parent or guardian’s written consent. You need to weigh at least 110 pounds. There’s no upper age limit for blood donation as long as you’re feeling well and meet the other criteria.
“Good health” means you aren’t currently sick, don’t have a fever, and aren’t taking antibiotics. You’ll also need to bring a valid form of identification, such as a driver’s license or passport. The specific ID accepted can vary by donation center.
Vital Signs Checked Before You Donate
At the donation site, staff will take your blood pressure, pulse, and temperature. FDA regulations set specific cutoffs: your systolic blood pressure (the top number) must fall between 90 and 180, and your diastolic (the bottom number) must fall between 50 and 100. Your pulse needs to be regular and between 50 and 100 beats per minute. If you’re outside those ranges on the day you show up, you’ll be asked to come back another time.
A small finger-prick test checks your hemoglobin level to make sure you have enough red blood cells to safely give blood. If your hemoglobin is too low, you’ll be temporarily deferred.
Medications That Affect Eligibility
Most common medications, including birth control, antidepressants, and over-the-counter pain relievers like ibuprofen, won’t disqualify you. The medications that do cause deferrals fall into a few categories, mostly because they either interfere with clotting or could harm an unborn baby if the blood were transfused to a pregnant woman.
Blood thinners like warfarin, rivaroxaban, and apixaban require a 7-day wait after your last dose. Anti-platelet drugs prescribed to prevent stroke or heart attack, such as clopidogrel and prasugrel, require a 14-day wait before donating platelets (though you may still be able to donate whole blood).
The acne medication isotretinoin (commonly known by its original brand name Accutane) carries a 1-month deferral because it can cause birth defects. The hair loss drug finasteride also requires a 1-month wait at the lower dose used for hair loss, or 6 months at the higher dose prescribed for prostate symptoms. Dutasteride, a similar prostate medication, requires 6 months as well.
A handful of medications result in longer or permanent deferrals. Certain drugs for psoriasis require a 3-year wait, and anyone who has ever taken growth hormone derived from human pituitary glands is permanently ineligible. If you’re enrolled in a clinical trial or received an experimental vaccine, you’ll typically need to wait 12 months.
Tattoos, Piercings, and Dental Work
Tattoos done at a state-regulated facility with sterile, single-use needles and ink are accepted with no waiting period in most states. The same applies to cosmetic tattoos like microbladed eyebrows, as long as they were done at a licensed establishment. If your tattoo was done in a state that doesn’t regulate tattoo shops, you’ll need to wait 3 months.
Piercings follow a similar rule. If the piercing was done with completely disposable, single-use equipment, you’re eligible right away. If reusable instruments were involved, or if you’re not sure, the wait is 3 months.
Minor dental work like fillings or a routine cleaning requires just a 24-hour wait. More invasive procedures, including tooth extractions, root canals, crowns, and dental implants, require 7 days. You also need to wait if you still have an unhealed wound or have been on antibiotics in the past week.
Travel Restrictions
Travel to areas where malaria is common triggers a deferral. Most travelers must wait 3 months after returning before donating. If you previously lived in a malaria-endemic area, the wait extends to 3 years. Anyone who has been diagnosed with and treated for malaria must wait 3 years after treatment and remain symptom-free during that time.
Travel-related deferrals also exist for certain regions connected to variant Creutzfeldt-Jakob disease (the human form of mad cow disease), though policies in this area have been relaxed in recent years. Your donation center will ask about your specific travel history during the screening questionnaire.
How Often You Can Donate
The required interval between donations depends on what you’re giving. For whole blood, you need to wait at least 8 weeks (56 days) between donations in the U.S. Platelet donations can be made more frequently, roughly every 4 weeks, because platelets regenerate faster than red blood cells. Double red cell donations, which collect twice the red blood cells in a single session, require a longer gap of about 16 weeks.
HIV Screening and Individual Risk Assessment
The FDA updated its blood donor eligibility guidance in 2023, replacing the previous policy that deferred men who have sex with men for a set time period. The new approach uses individual risk-based screening questions for all donors, regardless of sexual orientation. These questions focus on specific recent behaviors, such as having a new sexual partner or multiple partners, rather than blanket deferrals based on gender or orientation. All donated blood continues to be tested for HIV and other infectious diseases.
How to Prepare the Day Before
What you eat and drink in the 24 hours leading up to your appointment makes a real difference in how you feel during and after donation. Focus on iron-rich foods like red meat, eggs, poultry, fish, and leafy greens. Iron is important because donating a unit of blood depletes your iron stores, which can take about 8 weeks to fully replenish. Pairing iron-rich foods with vitamin C (citrus fruits, bell peppers, tomatoes) helps your body absorb more of it.
Hydration matters just as much. Losing a pint of blood temporarily reduces your blood volume, which can lower your blood pressure and cause dizziness. Drinking plenty of water before your appointment, and continuing afterward, helps minimize that lightheaded feeling. Avoid fatty foods right before donating, as high fat levels in your blood can interfere with the testing that’s done on every unit collected.