Can I Donate Blood If I Have Low Blood Pressure?

June 14 is World Blood Donor Day, and it comes just two days after the mass shooting in Orlando. The sheer number of casualties during the Pulse shooting generated an immediate need for blood, and reminded the world how crucial giving blood can be. If you're interested in being a blood donor, there are a few questions that might be on your mind, like can you donate blood if you have low blood pressure? There are a bunch of different factors that determine whether you can or cannot donate blood, so here's what you need to know.

The World Health Organization has made this year's World Blood Donor Day theme "Blood Connects Us All," which is particularly poignant in the wake of the shooting. And, although Orlando specifically is working hard to replenish its blood supply, it's not the only location that needs a constant stream of donations. According to the American Red Cross, someone in the U.S. needs blood every two seconds, and a single car accident victim can require as many as 100 pints of blood. Donating blood can save lives, and it doesn't require anything other than patience and a willingness to feel a little dizzy.

But not everybody can donate. It's an unfortunate fact that sexually active gay men are not permitted to donate blood. That's due to an FDA regulation, but other factors, like height and weight, genetic blood disorders, and drug use can also prevent donation.

So what about blood pressure? If you have low blood pressure, can you still participate in World Blood Donor Day? This is something I was wondering about, since I myself have low blood pressure that sometimes makes me feel like I'm going to swoon and throw up at the same time.

Here are the deets: the Red Cross says that, as long as your blood pressure is at least 80/50 (systolic/diastolic) and you feel well when you come to donate, you're good. Don't know your blood pressure? You can use an arm cuff — some grocery stores and pharmacies have them — for an exact reading, or you can approximate by finding your radial pulse. Just make sure to treat yourself right before and after you donate. Make sure you've eaten well and hydrated beforehand, or you'll feel even dizzier during donation. After-effects of donating blood include bruising around the area where blood was taken, a sore arm, and — you guessed it — fainting, so stay horizontal for a bit, and don't do anything strenuous for the rest of the day.

If you need help finding your nearest blood donation center, punch your zip code into the Red Cross' location finder. Easy, right? And if you live in the Orlando area, it's especially important that you go. Check out the Orlando-area locations below:

Images: TIME, Beartooth/Twitter