Shaved heads, dyed hair, billowing beards: Many are using their newly found free time to alter their appearances.

For some, those changes may be permanent. Stick-and-poke tattooing, which involves repeatedly pricking the skin, is proliferating among those at home, healthy and unhindered during quarantine.

Reddit’s r/quarantattoo thread is filled with guidance; a post on the site features group stick-and-pokes done over Skype, including one that depicts Joe Exotic, of “Tiger King.” More than 100 new members have joined a Facebook group called Stick and Poke Tattoo for Beginners in the past weeks. Kits, if you need one, are sold on Amazon and Etsy, but are sometimes sold out.

West Lacount, who owns Stick and Poke Tattoo Kit, a company that manufactures and ships at-home kits, has seen double the typical number of online orders, he said, a bump he usually only sees seasonally. “It has to do with being inside,” he said. “It’s like a long winter we’re all in.”

Three weeks ago, Jaelyn Suarez, 18, a high school senior in Miami, feeling listless, was scrolling through her phone around 3 a.m. when a notification popped up from her friend; it was a link to a YouTube tutorial on stick-and-pokes.

Ms. Suarez used a safety pin and pen ink to tattoo a small heart on her index finger, tracing the shape as she described each step to her friend on the phone. She said it felt like a prick for getting blood drawn, 45 times in a row. Her friend inked the same on her own finger.

According to many physicians, there are medical risks associated with this kind of tattooing. “There’s really no safe way to do it at home,” said Dr. Arash Akhavan, a dermatologist in New York City. “There’s probably a 25 to 50 percent chance you’re going to have some sort of complication.”

Bacterial infections, like staph and MRSA, can occur if the tattoo equipment isn’t sterile. Viral infections like hepatitis and H.I.V. can pass through needles. “There’s a reason tattoos are a heavily regulated, monitored industry,” Dr. Akhavan said.

Still, whether driven by boredom or the closure of traditional tattoo shops, many are trying it. An at-home kit costs about $50. And for some, tattoos are a way to assert control, at least over one’s body.

Quinn Milton, 28, an artist and game designer in Philadelphia, said stick-and-pokes provide an outlet for stress. Milton, who identifies as nonbinary, has given tattoos to both their roommates during quarantine; Milton is currently shading an abstract line drawing on the inside of their left arm, to pass the time.

Others use the tattoos as tributes. Gavin Morson, 27, of Newcastle, England, dedicated his 15th tattoo to the band Death Grips; the top of his foot now reads, “BOTTOMLESS PIT.” Stick-and-pokes are a grounding process for him, he said, an almost meditative way to anchor in the present. Besides, he said, “it’s hard to be bored when you’re in pain.”

The pain from stick-and-pokes can last beyond the actual prodding and piercing. Dr. Jason Emer, a dermatologist and cosmetic surgeon who owns a practice in West Hollywood, treated complications from amateur tattoos when he was a resident at Mount Sinai Hospital in Manhattan, caring for patients from the Rikers Island prison complex.

Necrotizing fasciitis, or flesh-eating bacteria, can infect a new tattoo, which can lead to the loss of a limb. If tattoo ink isn’t high quality, Dr. Emer said, you can have scar tissue form around the ink, which lumps and bumps to create little balls in the skin.

“The ink is the most important part,” said Inal Bersekov, a tattoo artist in Toronto, who has worked with Drake. Ink sold on eBay or Amazon may not be certified, Mr. Bersekov said. “It could just be printer ink. It’s a disaster. You can have heavy infections. It can even lead to death.” He’s “100 percent” sure he’ll get a flood of customers after quarantine, asking him to cover up their botched D.I.Y. tattoos, he said.

Those intent on giving themselves a stick-and-poke — “against all medical advice,” Dr. Emer stressed — should keep the area around the tattoo clean, using an over-the-counter antibacterial or antiseptic, and wear gloves and masks. Aftercare is essential. Dr. Emer recommended topical antibacterials, silicon-based scar gels and a peptide serum to help the skin seal.

Ruvianne Torres Fetsco, 25, a bartender in Harlem, keeps a sterile tattoo kit at home. They have 16 tattoos in total, 11 of which are stick-and-pokes, mostly reminders of “ridiculous bonding events” from art school, lounging in a living room with a group of friends and grabbing sewing needles and rubbing alcohol.

During quarantine, Torres Fetsco is tattooing a branch onto their hand. Every time they complete a goal, even a small task like cleaning their room or taking a walk, they adds a leaf onto the branch. The process becomes a calming ritual: They have a glass of wine, they watch “The Sopranos” in the background.

Kaila Arcenal, 21, a spa attendant in the Astoria section of Queens, watched “Twins Peaks” while working on her stick-and-poke, stopping periodically to snack on Oreos and oat milk.

She had Googled “simple cute stick and pokes” while bored and found a lumpy, frowning bear that she tattooed on her right ankle. The image will be a reminder of this time, she said, a remnant from a strange chunk of history. It’s also her “last-ditch effort” to have fun during quarantine.

“It’s a grumpy bear,” she said. “And right now, I’m a grumpy girl.”