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Getting a Shot? Chill Out

Freezing needle makes injections less painful, says doctor

WEDNESDAY, Oct. 3, 2001 (HealthDayNews) -- Tell the doctor to chill out if you're dreading his next needle.

Putting a needle in the freezer overnight cuts the pain from an injection by as much as 30 percent, says a San Francisco plastic surgeon.

"Everyone knows ice is a pain reliever," says Dr. Keith Denkler, associate clinical professor of plastic surgery at the University of California in San Francisco. "Doctors have long known that you can put ice on the skin, leave it there a while, give a shot, and it hurts less. And young teen-agers, when they pierce their ears, frequently use ice as a numbing agent."

Denkler says his twist on the technique is not to numb the flesh but to freeze the needle, then put it on a room-temperature syringe to give the injection. The idea is presented in a research letter in today's issue of The Journal of the American Medical Association.

"A lot of doctors use a substance called ethyl chloride, which they spray on the skin, and as a topical anesthetic it's a temporary freezing agent," he says. "The problem is that ethyl chloride's toxic to breathe, and it's not the greatest thing for pregnant women. And while my original concept was to find something to crush and put against the skin, it all of the sudden dawned on me: Why not freeze the needle?"

Denkler put a couple of needles in the freezer overnight and tested the concept on himself.

"I had my assistant poke my arm with a frozen needle and then with a non-frozen needle, and I noticed a difference -- about a 20 to 30 percent decrease in pain. I then tried it on my assistant and she felt the same thing."

But would his patients notice any difference?

"In my practice, I administer botulism toxin shots, or botox, for frown lines," Denkler says. Botox paralyzes the muscles around the eyes and diminishes crow's feet and frown lines between the eyebrow and the nose. "While it's quite popular here in Marin County, the shot is quite painful."

Smoothing the lines between the eyebrows at the top of the nose takes a Botox shot to the right frown line and one to the left frown line, Denkler says. So he had his nurse hand him either a frozen 30-gauge needle or an identical needle at room temperature to see if 77 patients noticed any difference. "I didn't know which one was frozen or not, nor did the patients," he says.

The frozen needle was less painful for 59 patients, while 14 said they were more painful; four noticed no difference. Using a pain scale of zero to 10, Denkler says 83 percent of the injections with a frozen needle registered a low 1 or 2 compared with 58 percent of the room-temperature needles. On average, the room-temperature needles were almost twice as painful as the frozen ones, he says.

Denkler says nerves can handle only one stimulus at a time, and that may be why patients experience less pain. "The nerves are occupied with cold and may have trouble distinguishing between cold and pain." He says he doesn't know why some patients felt more pain.

"It's an interesting idea," says Dr. Robert Bernard, vice president of the American Society for Aesthetic Plastic Surgeons and a private practitioner in White Plains, N.Y. "But before recommending this on a universal level, I would want to see additional studies in different clinical settings -- injections for diabetics for instance."

Bernard says it's not the needle that causes the pain, but what's being injected. "What causes the discomfort is the volume and the acidity of the solution that's being injected. Passing the injectable solution through a frozen needle, and changing the temperature of that solution may alter the efficacy of the injection," Bernard says. "That would have to be tested out."

What To Do

Denkler says cold needles could help people who need an daily injections. "Putting their needles in the freezer could make the injection less painful for them."

For more on how to cope with the pain of an injection, check the Needle Phobia Page or Pediatric Pain.

This British site has a how-to plan to get over needle phobia.

SOURCES: Interviews with Keith Denkler, M.D., associate clinical professor of plastic surgery, University of California at San Francisco, and Robert Bernard, M.D., vice president, American Society for Aesthetic Plastic Surgeons, White Plains, N.Y.; Oct. 3, 2001, The Journal of the American Medical Association
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