Along with its needed effects, sumatriptan (the active ingredient contained in Imitrex) may cause some unwanted effects. Although not all of these side effects may occur, if they do occur they may need medical attention. Find patient medical information for Imitrex Oral on WebMD including its uses, side effects and safety, interactions, pictures, warnings and user ratings. According to the official site for Cymbalta, the most common side effects experienced when taking it are: nausea, dry mouth, sleepiness, fatigue, constipation, dizziness, decreased appetite, and increased sweating Topamax, Depakote, amytriptylines, nortriptylines, beta blockers, calcium blockers, Neurontin, other anti-depressants, cymbalta, etc. Also have used relpax, imitrex. I take Cymbalta for fibromyalgia and I still get severe migraines. My doctor prescribed Imitrex. In the past before I started taking Cymbalta, my dose was 100mg. now that I take Cymbalta I have. Our Imitrex Side Effects Drug Center provides a comprehensive view of available drug information on the potential side effects when taking this medication. This is not a complete list of side effects and others may occur. The most common side effects of duloxetine are nausea, dry mouth, constipation, diarrhea, fatigue, difficulty sleeping, and dizziness. Increased blood pressure can occur and should be monitored. Imitrex (sumatriptan) is a headache medicine that narrows blood vessels around the brain. Sumatriptan also reduces substances in the body that can trigger headache pain, nausea, sensitivity to light and sound, and other migraine symptoms. Summary. Drug interactions are reported among people who take Imitrex and Cymbalta together. This study is created by eHealthMe based on reports of 555 people who take Imitrex and Cymbalta from FDA, and is updated regularly. Side effects of Cymbalta that are different from Lyrica include diarrhea, difficulty sleeping, increased blood pressure, seizures, and sexual dysfunction (decreased sex drive and delayed orgasm and ejaculation).