My sister started taking Cymbalta for Fibromyalgia and her appetite dropped a lot, and just a few months later she was pre-diabetic. I have read some other people's comments saying that going on or even going off of cymbalta has really messed up their blood sugar. Did it help u lose or gain more weight?The reviewer seemed to have gained weight with other pain med regiments. Did the cymbalta add to the problem or was there a significant drop or change in weight. Cymbalta Side Effects: An Introduction As with any medicine, there are possible side effects with Cymbalta ® (duloxetine hydrochloride). However, not everyone who takes Cymbalta will experience side effects. Doctors prescribe Cymbalta to treat depression, anxiety, and some chronic pain disorders. Research suggests that taking Cymbalta can cause modest changes in body weight. Learn more here. Cymbalta (Duloxetine) is used to treat depression. The drug is in a class of antidepressants called serotonin-norepinephrine reuptake inhibitors (SNRIs). Ive been on duloxetine/cymbalta for about 4 months and i was about 150 and i am now 128 and still losing. I am not sure if any one else has had this but its kinda strange. Cymbalta and Prozac are both approved by the U.S. Food and Drug Administration to treat depression. Cymbalta is also approved to treat generalized anxiety disorder, diabetic nerve pain and fibromyalgia, while Prozac is also approved to treat obsessive-compulsive disorder, bulimia nervosa and panic disorder. Clinical studies of Cymbalta and weight loss have shown that up to 9 percent of people taking the medication reported a loss of appetite, and up to 2 percent of the people reported weight loss. Cymbalta is the brand name for the drug duloxetine. It belongs to a class of drugs called serotonin-norepinephrine reuptake inhibitors (SNRIs). SNRIs work by changing the balance of the chemical. Cymbalta is the name-brand version of the drug duloxetine, which is used to treat generalized anxiety disorder and depression, as well as to treat pain and tingling associated with certain diseases and conditions. Cymbalta may spur a variety of side effects, including weight loss or weight gain.