The Injection That Melts a Double Chin

I sat back, exposing the vulnerable area under my chin, bracing myself for the pinch of the needle. I clutched an ice pack, ready to apply it, and looked around as my heart raced. I was about to have vials of synthetic stomach acid shot into my double chin, erasing it, I hoped, forever.

The drug designed to treat my “submental fat” (the fat pocket under the chin) is the new cosmetic injectable Kybella, which promises to dissolve fat cells through a series of injections. There’s very little downtime, it’s noninvasive and nonsurgical, and there’s little risk. The drug is the first (and only) injectable designed to contour away the dreaded double chin.

Approved by the FDA in 2015, Kythera Biopharmaceuticals’ drug (which has since been acquired by Allergan) hit the market as an alternative to liposuction or surgery, using a synthetic version of deoxycholic acid—a salt found in human bile that aids fat digestion—to destroy fat cells. In the digestive tract, deoxycholic acid breaks down fat by destroying the cell membrane. When injected into subcutaneous fat, this cytolytic drug does the same thing—in targeted locations. The dissolved fat is now cellular debris, and gets cleared into the lymphatic and circulatory systems by specialized immunologic cells. This happens gradually over the span of several weeks. As for the deoxycholic acid, it follows the same path; it gets