But while the connection was not established, medical experts said the NIU incident stressed stopping antidepressant therapy without directions from doctors is risky.
Prozac, a branded anti-depressant medication, with the generic name fluoxetine hydrochloride, is the third most prescribed anti-depressant drug in the U.S. In 2006, over 23.1 million prescriptions for fluoxetine hydrochloride were made.
It has FDA approval for treatment of clinical depression, obsessive-compulsive disorder, bulimia, panic disorder and even premenstrual dysphoric disorder. At least one-fifth of its users who halt their use reported a variety of syndromes including abdominal pain, crying bouts, dizziness, irritability and a sharp sensation on the limbs akin to an electric shock.
Kazmierczak's ex-girlfriend Jessica Baty told CNN he stopped taking Prozac because it made him feel like a zombie. However, Baty did not disclose if her former boyfriend merely followed his doctor's advice or decided to stop on his own.
For some users, stopping anti-depressant medicine may cause the patient to feel worse for a brief period as their bodies adjust to the change. Prozac and other similar drugs work on the serotonin, a chemical messenger in the human brain, which delivers signals that affect the mood, appetite and sexuality of the patient.
While some experience the zombie-like feeling described by the NIU gunman, others have the opposite reaction wherein they are ushered into a state of extreme restlessness.
Low dosage of anti-depressants produce the least side effects. The U.S. FDA in 2004 mandated pharmaceutical firms to place a warning label on Prozac and similar drugs that it may provoke suicidal thoughts among young people.
