The American Red Cross is sending a plea for your help.
The blood supply is at a 10-year low across the country as seasonal illnesses, rising COVID cases and holiday travel threaten to make the shortage even worse.
"We are sometimes at less than a half-day's supply for certain blood types," Dr. Baia Lasky with the American Red Cross said. "And really, the blood is leaving our shelves as fast as we can collect it."
Now, at some hospitals, leaders are worried patients will start feeling the pain.
"There is a possibility, if our blood type O levels get so low, that we would have to cancel elective surgeries," Dr. Kristin Mekeel with UC San Diego Health said.
One of San Diego's largest health care systems is sounding the alarm, telling reporters it aims to keep 80 to 90 units of blood on the shelf but lately, it's short. A single trauma patient can consume 100 units.
"Just trying to keep enough blood on the shelf in case one of those emergency cases, such as a trauma or childbirth or other medical bleeding came in so we would have blood available to give the patients emergently," Mekeel said.
You can give blood if you're older than 17 — or in some states you can be 16 with a parent's consent. You also have to weigh at least 110 pounds and have an FDA-approved COVID vaccine. Plus, you can't donate more than once every 56 days and not more than 6 times in a year. Most of us meet those parameters.
San Diego Blood Bank CEO Doug Doug Morton said: "There's no better, more precious gift than giving the gift of life."