You’ve heard of tennis elbow — but barista elbow?

As the demand for specialty coffee drinks continues to grow — in the United States alone, it’s a $30-billion-a-year business — java slingers are suffering severe injuries.

“I grabbed a gallon full of milk and felt a sharp pain in my left wrist,” says Samantha Lino, 23, a former Starbucks barista. “I struggled not to drop it.”

That was last June. The pain kept Lino up all through the night, and the next day she couldn’t move her arm. She went to the doctor right away.

“She said it was medial epicondylitis” — golfer’s elbow, caused in this case by the repetitive stress of lifting heavy pitchers of milk and making multi-step drinks in complicated machines.

“I’ve seen all kinds of barista injuries,” says Phaeleau Cunneen, a certified hand specialist at SPEAR Physical Therapy in Manhattan. “It’s very common, and usually chronic.”

The motions involved in making and serving coffee are far more dangerous than the average person knows, Cunneen says.

To make an espresso, for example, “you have to stamp the espresso, push it into the machine, then turn the knob — and the person running the machine is probably making 100-300 cups a day, maybe more.”

Even shuffling things behind the counter can cause debilitating injuries.

“Lifting all those milk gallons — the elbows are taking a big strain,” he says.

Alex Bernson, a barista advocate who worked in high-end city cafés for the past two years, conducted an informal survey for the coffee-centric site Sprudge. Of the 475 baristas who responded, 55 percent said they had sustained repetitive stress injuries.

“I know someone with a fused vertebrae from constantly looking down at the machine,” says Bernson, who himself sustained an RSI in his shoulder. “I’d like to see a real study and know what’s really going on.”

Treatment for RSI ranges from physical therapy to cortisone shots to surgery, Cunneen says. There are also preventive measures, including exercise to build muscle and better posture.

Six months later, Lino’s left arm is still in a sling and she takes up to 12 Motrin a day. She’s afraid she’ll need surgery that she won’t be able to afford.

Her doctor did give her one piece of advice, which she took: Quit.

“She basically said, ‘You shouldn’t be doing this anyway — it’s a s—ty job.’ ”