Prozac and the other SSRIs can exact a high price for their benefits. Prozac is considered better than the older drugs because "only" 17 percent of the people who try it have to stop because of negative experiences, compared with nearly a third (31 percent) of the patients taking the tricyclic drugs. The reported side effects of Prozac, listed in percentage of incidence, include nausea (21 percent), headaches (20 percent), anxiety and nervousness (15 percent), insomnia (14 percent), drowsiness (12 percent), diarrhea (12 percent), dry mouth (9 percent), loss of appetite (9 percent), sweating and tremors (8 percent), and rashes (3 percent). In my own practice, and in reports from others, I believe these percentages are far too low, and that the true incidence of side effects is much higher. This discrepancy is likely due to the limited time span in the initial studies (only four to six weeks), and to the relatively small number of subjects.
The SSRIs also reduce sex drive. Studies that looked specifically at sexual dysfunction found that 34 percent of all men and women using Prozac had a drop in libido or difficulty in attaining orgasm. Again, in my experience, the figure is much higher. Many patients do not mention this as a side effect for a number of reasons, including embarrassment and the fact that sex simply isn't an issue for some people. For others, the loss of sex drive is balanced out by the reduction in depressive symptoms.
Prozac is also more likely than other antidepressants to cause restlessness and agitation. Some people have even experienced violent or destructive outbursts, and the drug's association with suicide remains controversial.
Zoloft and Paxil are similar to Prozac in terms of their side effects. However, Paxil tends to be more sedating, making it preferable for people with anxiety or insomnia. Zoloft generally falls in between the stimulating Prozac and the sedating Paxil, but individuals will differ in their responses.
The newest SSRI is Serzone (nefazodone hydrochloride), which is especially useful in cases of agitation, anxiety, and insomnia. Side effects were mild in a 2,200 patient sample, according to a manufacturer's pre-marketing trial. It appears to have the lowest incidence of sexual dysfunction of all the SSRIs, and also appears to be more effective in reducing suicide risk.
The Other Antidepressants
There are antidepressants that don't fall into any of the established classes: Wellbutrin, Desyrel, and Effexor.
Wellbutrin (bupropion hydrochloride) seems to boost norepinephrine function, with no impact on serotonin levels. Chemically related to amphetamine, it usually has a more energizing effect than the other synthetic drugs. Wellbutrin does not affect the heart or libido as do antidepressants, so it is often used to treat depression in individuals who have problems in these areas. It has also proved useful in the treatment of bipolar depression and a condition known as attention deficit disorder, which is characterized by impulsive behavior and a short attention span.
The main difficulty with this drug is its association with seizures. While this problem appears to be dosage related, Wellbutrin has been found to cause seizures in 1 in every 200 persons who take it. Psychiatrists tend to shy away from it for this reason, although a new timed-release version may eliminate this problem. Other side effects include restlessness, insomnia, irritability, and headache. Wellbutrin must be taken three times per day, another inconvenience, to maintain a relatively stable concentration level in the blood.