Smiling During an Injection Can Help With Pain and Stress, Study Finds

As COVID-19 vaccines loom on the horizon, a new study may help people mentally prepare to receive the shot—helping make the situation a little less stressful. According to the study, when recipients smiled before a shot—a true smile, not a grimace—they reported lower levels of pain than people who didn’t smile before receiving a similar shot.

While laugh therapy has been explored in the past for aging patients and those living with long-term or debilitating illnesses, this study marks a new protocol for administrating medicine to shot-phobic patients. The November study was published in the journal Emotion.

Scientists gave subjects a shot of saline using a similar dosage that one might receive in a vaccine. The researchers asked users to smile just prior to receiving the shot and then asked the recipients to report on their pain levels. In order to ensure the patients smiled, researchers Tara Kraft-Feil and Sarah Pressman had them engage the proper facial muscles by having participants hold chopsticks in their mouths.

“In our study, faking a big, Duchenne smile before and during a sham vaccination not only made the needle hurt about half as much, but it also made people anticipate that the needle would hurt less before they got it," Sarah Pressman, PhD, a professor of psychological science at the University of California, Irvine and the study’s lead author, tells Verywell. "In addition, it reduced the physiological stress response associated with needle anxiety.”

During stressful situations, our heart rate accelerates, according to Pressman. “But for those individuals who were Duchenne smiling, their heart rate stayed lower before, during and after the needle,” she says.

Smiling Alleviates the Stress

In order to maintain the purity and accuracy of their results, researchers told the participants a cover story. “Because we didn't want our subjects to know the purpose of the study, we told them that we were interested in the effects of multitasking on their needle experience,” Pressman says. “That way they had a reason for why they were holding chopsticks in their mouths in different positions.”

For the study, researchers used a 25 gauge needle, which according to Pressman is likely the same size needle that will be used in future COVID-19 vaccination, "so the same rules should apply," she says.

Some subjects assumed a Duchenne smile, others, a "social smile" that involved only the mouth.

Those who smiled through the stressful task exhibited lower heart rate levels compared to those that maintained a neutral expression.

"Some of the forced smilers received an instruction to smile along with the chopsticks; they showed even less stress than those who got no instruction," Pressman says. "The Duchenne smilers had lower stress numbers than the social smilers, though the data was insufficient to draw a conclusion.”

For those preferring to stay with their tried-but-true method of closing their eyes or holding their breath, Pressman suggests smiling will be less painful. “The mechanism behind why we think smiling helps is that it tricks your brain into believing that you are happy via the backward signal that your facial muscles send via nerves to your brain," she says. "This idea is called the facial feedback hypothesis, but this concept has been around since the time of Darwin.”

Why It Works

The idea here is that smiling makes you feel more positive, according to Pressman. "In our work and the work of others, positive emotions are the ultimate stress antidote," she says. "As you can imagine, it's hard to feel stress and anxious at the same time [if] you are happy.”

Pressman says they believe there are three reasons positive emotions are helpful in stressful situations:

1. It makes you believe the stressor is less threatening, lowering anxieties and making you believe you've got a handle over the situation.
2. Being in a good mood has been shown to decrease psychological and physical responses to the stressor.
3. Positive emotions help you recover and get over stressful experiences faster, helping you return to your resting state.

While holding your breath or tightly shutting your eyes may not produce the same benefits, Pressman says it may certainly still help.

“Squeezing your eyes really tightly can activate those same orbicularis occuli muscles we are interested in, and we truly think that that muscle activity is one of the keys to this benefit,” she says. “We also think that this is one of the reasons people naturally have this response to pain because it helps, and in our work, this type of tight facial grimace did reduce stress and pain, it just didn't help on the physiological end.”

The researchers hope this can encourage people to get vaccinated even if they're nervous about the pain associated with a shot.

“Our findings could be quite helpful for people who may be apprehensive about receiving vaccines due to the pain and stress associated with needle injection,” study co-author and child psychologist in North Dakota Tara Kraft-Feil, PhD, tells Verywell. “In the midst of 'flu shot' season and with the COVID-19 vaccine becoming available soon, people should know that smiling while receiving their vaccine will likely make that experience less painful and physiologically stressful.”