The first wave of litigation over Cymbalta withdrawal symptoms is going to trial, while thousands of other plaintiffs wait for the results.

Cymbalta is manufacturer Eli Lilly’s brand name for the drug duloxetine. Since being approved by the FDA in August 2004, Cymbalta has been approved as a treatment for major depressive disorder, generalized anxiety disorder, diabetic peripheral neuropathy, fibromyalgia, and chronic musculoskeletal pain.

Eli Lilly developed Cymbalta to fill a void left in sales when the company’s patent for Prozac expired in 2001. Cymbalta became Eli Lilly’s best-selling drug until it lost patent protection. Cymbalta sales from 2004 through 2011 totaled around $18 billion, with annual sales peaking at nearly $5 billion per year.

Despite its popularity, the trouble with Cymbalta for many users is the occurrence of withdrawal symptoms when they try to stop taking the drug. Patients have reported symptoms so severe they made discontinuing the drug almost impossible.

Probably the most dramatic of these symptoms is what are commonly described as “brain zaps,” a sense of electrical shocks inside the head. These sometimes co-occur with nausea, vomiting and dizziness. Other symptoms reported include fatigue, vertigo, insomnia, headache, tunnel vision, and mood disturbances such as anxiety and irritability.

Patients in some cases have reported their Cymbalta withdrawal symptoms continued for as long as several months, or in some cases over a year, after they stopped taking the drug. Some say they had to resume taking Cymbalta to make the symptoms go away.

Cymbalta Lawsuits

Over 5,000 Cymbalta lawsuits have been filed over these withdrawal symptoms. Generally, the plaintiffs say Eli Lily underrepresented the risk of withdrawal symptoms on the drug’s label while simultaneously overstating the drug’s effectiveness. They say Cymbalta withdrawal led to additional medical bills, lost hours at work, and considerable loss of quality of life.

In early August, a jury in Los Angeles returned a decision in favor of defendant Eli Lilly in the first such Cymbalta lawsuit to go to trial. The plaintiff in that case said that when she tried to quit Cymbalta after six years of use, she suffered from brain zaps, anxiety, insomnia and dizziness.

The plaintiff’s attorneys had argued that Lilly had failed to disclose that as many as 44 percent of Cymbalta users reported discontinuation side effects. The label for Cymbalta reflected that discontinuation symptoms occurred at a rate of only one percent or greater.

The FDA issued warning letters in 2007 and 2010 saying Lilly had overstated the drug’s effectiveness and understated possibility of side effects like abdominal bleeding and liver damage.

According to one Cymbalta class action lawsuit, the company may have taken advantage of the habit-forming nature of Cymbalta to recruit new patients.

Plaintiffs say Eli Lilly used a promotional campaign called the “Cymbalta Promise” in which new patients would get a 60-day supply of Cymbalta to try for free. The plaintiffs say that 60 days happened to be the length of time in which Cymbalta withdrawal symptoms started appearing in about half the patients studied in clinical trials.