Though Prozac is one of the world's best-known commodities, its most terrifying potential side effect, "akathisia," remains virtually unknown. Akathisia has been described as a unique form of inner torture that, prior to the development of psychiatric drugs, probably never existed. Knowledge of the side effect, however, has been around for a while. In 1978, 10 years before "fluoxetine" would be brought to the US market and become the bestseller known as Prozac, initial clinical trails had already warned of akathisia and other problems. Minutes from Lilly's Prozac project team in that year noted that, "Some patients have converted from severe depression to agitation within a few days; in one case the agitation was marked and the patient had to be taken off [the] drug . . . There have been a fairly large number of reports of adverse reactions."

As the Forsyth case and others would go on to reveal, Lilly's internal records revealed considerable awareness within the company. A letter sent to them from the British Committee on Safety of Medicines in 1984 reads: "During the treatment with [Prozac] 16 suicide attempts were made, two of these with success. As patients with a risk of suicide were excluded from the studies, it is probable that this high proportion can be attributed to an action of the preparation." Similar concern was expressed by German authorities in 1985, where Prozac is sold as "Fluctin," and with required warnings of possible akathisia and suicide. A Lilly document dated from March of that year even quantifies the problem, suggesting a rate of suicide for Prozac 5.6 times higher than for the antidepressants that were popular before the rise of the SSRIs – the tricyclics. "The benefits vs. risks considerations for fluoxetine [Prozac] currently does not fall clearly in favor of the benefits," the document concludes. By 1986, clinical-trial studies comparing Prozac with other antidepressants showed a rate of 12.5 suicides per 1,000 users compared to only 3.8 per 1,000 on older, non-SSRI antidepressants, and 2.5 per 1,000 on placebos.

After Prozac's entry into the market in 1988, reports quickly surfaced to confirm that the beast Lilly saw in the laboratory had now, without warning, been unleashed upon the public. In 1990, a report appeared in the American Journal of Psychiatry on the "Emergence of Intense Suicidal Preoccupation During Fluoxetine Treatment." Two Harvard psychiatrists and a registered nurse described cases in which patients developed serious preoccupations with suicide soon after being given Prozac. "We were especially surprised to witness the emergence of intense, obsessive, and violent suicidal thoughts in these patients," they commented. "It was also remarkable how violent these thoughts were. Two patients fantasized, for the first time, about killing themselves with a gun, and one patient actually placed a loaded gun to her head. One patient needed to be physically restrained to prevent self-mutilation."

Two years later, in July 1992, another article appeared, this time in the Archives of General Psychiatry. Again, the article had two senior researchers among its authors, one of whom was a leading expert on akathisia. The psychiatrists stressed in the report that, prior to going on Prozac, none of their patients had a history of significant suicidal behavior. "All described their distress [while on Prozac] as an intense and novel somatic-emotional state; all reported an urge to pace that paralleled the intensity of the distress; all experienced suicidal thoughts at the peak of their restless agitation; and all experienced a remission of their agitation, restlessness, pacing urge, and suicidality after the fluoxetine [Prozac] was discontinued."

The finding that these problems emerge soon after an SSRI drug is taken, and then disappear soon after the drug is withdrawn, provides compelling evidence that the problem is often the drug and not, as the makers of SSRIs have insisted, the depression. Anthony Rothschild and Carol Locke, also of Harvard Medical School, reported three such cases in the Journal of Clinical Psychiatry in 1991. All three individuals had previously attempted suicide while being treated with Prozac – in fact, each had jumped from great heights and had managed to survive. In turn, all three had been put back on Prozac, only to complain of the same strange desire to kill themselves.

"I tried to kill myself because of these anxiety symptoms. It was not so much the depression," said one of the individuals, a 25-year-old woman. Another, a 47-year-old man, complained that "this is exactly what happened the last time I was on [Prozac], and I feel like jumping off a cliff again." Reflecting on these cases, the Harvard researchers stressed that patients need to know that such overwhelming symptoms are the side effects of medication, and are treatable. "Our patients had concluded their illness had taken such a dramatic turn for the worse that life was no longer worth living."