The painful and debilitating symptoms experienced by countless patients discontinuing the anti-depressant Cymbalta (duloxetine) have resulted in a flood of Cymbalta lawsuits accusing drug giant Eli Lilly of concealing the drug’s withdrawal effects.

While Eli Lilly marketed that 1 percent to 2 percent of users experienced withdrawal side effects, described as agonizing by many who have gone through it, at least 44 percent to 50 percent of Cymbalta patients actually experienced them, according to one Cymbalta withdrawal lawsuit which cited a 2005 article in the Journal of Affective Disorders.

Other studies have found that figure to be as high as 78 percent.

The same article noted that data compiled during Eli Lilly’s clinical trials for Cymbalta were gathered only from patients who voluntarily shared their symptoms. Had Eli Lilly used the more accurate “symptom checklist,” the results would have yielded even higher incidence rates, it is alleged.

Since hitting the U.S. market in 2004, Cymbalta has been the subject of controversy.

First approved as a treatment for major depressive disorder, the U.S. Food and Drug Administration (FDA) soon granted approval for Cymbalta as a treatment for generalized anxiety disorder (GAD), followed by approval to treat fibromyalgia — a condition manifested by chronic body pain and tenderness in the joints, muscles, tendons, and other soft tissues — in 2008.

By 2009, the FDA responded to complaints about Cymbalta’s severe withdrawal effects by posting information on its website about Cymbalta Discontinuation Syndrome, noting that there are thousands of Internet entries addressing Cymbalta withdrawal trauma.

Withdrawal symptoms reported by Cymbalta users include extreme mood swings, anger, irritability, electric-shock sensations in the body and brain known as “brain zaps,” physical and neurological problems, dizziness, nausea, vomiting, vertigo, excessive sweating, insomnia, nightmares, diarrhea, suicidal thoughts, involuntary laughing or crying, hypomania, tinnitus and seizures.

The FDA has published claims that Cymbalta discontinuation syndrome is more severe and much more widespread than acknowledged by Eli Lilly and that Lilly sales representatives and marketing materials do not adequately inform physicians about the likelihood and severity of discontinuation syndrome.

In 2012, Eli Lilly amended the drug’s label to warn of the withdrawal symptoms, which according to the label include dizziness, nausea, headache, paresthesia, fatigue, vomiting, irritability, insomnia, diarrhea, anxiety, and hyperhidrosis.

Also in 2012, a Cymbalta class action lawsuit was filed against Eli Lilly for allegedly concealing the withdrawal risks while raking in some $18 billion in Cymbalta sales between 2004 and 2011.

“Instead of honestly disclosing the risks associated with Cymbalta withdrawal and letting consumers and prescribing healthcare professionals decide if Cymbalta was worth the risk, Lilly engaged in unfair and unlawful marketing practices,” according to the Cymbalta class action lawsuit.

Cymbalta is in a class of anti-depressants known as serotonin-norepinephrine reuptake inhibitors (SNRIs).

Cympalta withdrawal lawsuits have alleged that because Cymbalta’s half-life is less than one day, and Cymbalta is generally administered once daily, it is possible for patients to experience Cymbalta withdrawal symptoms after simply forgetting to take one dose. This also means that users cannot safely taper off of the drug by taking a capsule every other day.