Prozac is a very strong mood altering drug. Therefore, it is extremely important to take the exact Prozac dosage as directed by your physician. To deviate from his or her prescription can be dangerous and even fatal. Your doctor will also discuss possible interactions with other drugs that might cause your serotonin levels to spike too high. Also, he/she will want to talk to you about a possible increase of suicidal thoughts and tendencies. If you experience any of the negative side effects of the drug, it will be extremely important to contact your doctor, and have the Prozac dosage altered to a safer level.