Eli Lilly, the maker of Cymbalta, is facing a class action lawsuit investigation over alleged Cymbalta withdrawal symptoms.

Going off antidepressants have been alleged to cause “antidepressant discontinuation syndrome.” This is technically distinct from “drug withdrawal” as it is not a drug withdrawal per se, as the body is not necessarily dependent on Cymbalta and other antidepressants through the same mechanisms involved as other drugs, but instead is believed to result from a chemical imbalance caused by changes in neurotransmitter levels.

Patients suffering from “discontinuation syndrome” do not necessarily crave the drug or exhibit drug-seeking behaviors as someone would with an opiate or other drugs. But the distinction is somewhat subtle and esoteric.

Starting in 2013, the early stages of a large Cymbalta withdrawal class action lawsuit began to coalesce. This Cymbalta lawsuit alleges that Eli Lilly was aware of Cymbalta withdrawal symptoms like “brain zaps” and other serious symptoms that appeared when patients stopped taking Cymbalta.

Brain zaps are a symptom described by patients allegedly suffering from side effects of Cymbalta withdrawal. In this symptom, patients allegedly suffer from a sensation of being electrocuted in the head.

Other Cymbalta withdrawal lawsuits have alleged that Eli Lilly deliberately downplayed these risks from Cymbalta patients. Lawsuits similar to the Cymbalta lawsuit often allege that drug makers did not do enough to protect the public from a drug’s side effects, and may seek to recoup the cost of medical care, compensation for lost wages, and other costs.

Meanwhile, documents from the U.S. Food and Drug Administration (FDA) reflect concerns that Cymbalta withdrawal is more serious than Eli Lilly implied. A presentation dated in 2009 shows that the FDA had received reports of Cymbalta withdrawal, including the infamous brain zaps.

The presentation also suggested that psychiatric effects of Cymbalta withdrawal were serious enough to interfere with patients’ professional and social relationships.

Additionally, the FDA presentation expressed concerns that patients’ relationships with their doctors would be damaged, as the prescribing information for Cymbalta did not reference these side effects of Cymbalta, potentially straining the relationship between doctors and their patients.

Lastly, the FDA presentation hinted that Eli Lilly’s methods for dealing with complaints may have been downplaying reports of the side effects of Cymbalta, both to patients going through Cymbalta withdrawal and by avoiding a damning paper trail. According to the FDA presentation, call centers run by Eli Lilly did not keep adequate records of interactions related to alleged cases of Cymbalta withdrawal.