Here’s something to think about if you’re considering Botox injections. A new study finds people who receive the treatments to decrease their wrinkles may also lessen their ability to completely feel emotions.

A side effect of the popular cosmetic injection is frozen muscles, meaning the face doesn’t as readily display emotion. But scientists have long thought it also works the other way, that facial expressions can also influence the brain about how we feel.

The lead author of the study in the journal Emotion described it as a continuous feedback loop.

The study participants were shown three types of videos that would evoke a negative reaction, a positive one and a mildly positive response. They rated their emotional reactions according to a scale. After Botox treatment, they repeated the procedure.

There was a significant decrease from the first to second ratings in how strongly the Botox group felt their emotions. The biggest difference was in the mildly-positive video category. Researchers speculate that maybe facial expressions are more important in cases where the emotions are relatively mild.

The response from cosmetic dermatologists? They say that that Botox dosage plays a big part. And that more doctors now tend to be conservative with dosage, allowing more facial movement. They also say most patients report improvement in mood and self-confidence after Botox.