Are you one of the millions of people in this country taking an SSRI? This popular class of antidepressant includes Celexa (citalopram), Luvox (fluvoxamine), Paxil (paroxetine), Prozac (fluoxetine), and Zoloft (sertaline).

If you are taking an SSRI, have you noticed any sexual problem arising since you started taking the drug, such as loss of sexual desire, difficulty achieving orgasm, or a problem related to penile erection or vaginal lubrication? If yes, then welcome to the club. Recent research indicates that from one third to more than one half of patients taking an SSRI experience some form of sexual dysfunction.

The SSRI revolution

Drug therapy for depression has undergone explosive growth in this country since the introduction in the late 1980s of Prozac, the first SSRI. In the first decade of the SSRI revolution, the percentage of outpatient psychiatric visits resulting in the prescription of an antidepressant more than doubled (from 23% to 49%). By 1999, Prozac, Zoloft, and Paxil were, respectively, the 10th, 11th, and 15th most frequently prescribed drugs in the country. And according to one industry source (InfoScriber’s Clinical Pharmacology Network), by March 20, 2001, the four leading SSRIs (Prozac, Zoloft, Paxil, and Celexa) accounted for 50% of all antidepressant prescriptions.

SSRIs have made these rapid and remarkable gains because they are just as effective as the older tricyclic antidepressants and monoamine oxidase inhibitors, but far safer, with fewer side effects. However, as beneficial and widely prescribed as SSRIs are, like their predecessors they can cause significant sexual dysfunction.

A hidden problem (easily revealed)

In the early clinical studies of SSRIs, the reported rate of sexual side effects was low, ranging from 2% with Prozac to 16% with Zoloft, but recent research suggests the overall rate of sexual problems with SSRIs, as a group, may exceed 50%. How do we account for this broad discrepancy? One explanation can be found in the methodology of the early clinical studies. Researchers in those studies generally relied on patients to volunteer the fact that they were having sexual problems. This approach may work just fine when it comes to assessing the rate of side effects like nausea, vomiting, or headache, but it’s practically a matter of conventional medical wisdom that patients are generally reluctant to volunteer to their doctor that they’re experiencing sexual difficulties.

In one study, Montejo-Gonzalez and colleagues interviewed 344 psychiatric outpatients, who were being treated with an SSRI, about specific sexual side effects. The majority--68% of the men and 72% of the women--were being treated for major depression. These patients had normal sexual function before being placed on SSRI therapy and were screened for any other conditions or behaviors that could have caused sexual dysfunction. Overall, 58% (200 patients) reported some form of sexual dysfunction within two months after starting SSRI therapy. On the whole, all four SSRIs taken by these patients demonstrated an equivalent potential for sexual side effects.

Interestingly, of the 200 patients reporting sexual dysfunction, only 28 (14%) mentioned it voluntarily; the rest admitted a problem only when asked directly about specific sexual side effects. This finding echoes an earlier study of the tricyclic antidepressant clomipramine: one third of the patients answered ‘yes’ to a vague question about "sexual difficulties"; however, when asked specifically about difficulty achieving orgasm, 96% of the patients admitted having a problem.

New study in 6300 patients

In the largest study of antidepressant-induced sexual dysfunction ever undertaken, Clayton and colleagues surveyed 6,297 people taking an antidepressant. The antidepressants under study included all of the newer antidepressants: SSRIs; SNRIs (serotonin/norepinephrine reuptake inhibitors) including Serzone (nefazodone) and Effexor (venlafaxine); and the nonSSRI/nonSNRIs Wellbutrin (bupropion) and Remeron (mirtazepine). Clayton et al reported an overall rate of sexual dysfunction in this population of 37%. Sexual problems were significantly less common among patients taking Wellbutrin or Serzone than among those taking Effexor, Paxil, Prozac, or Zoloft. Patients taking Wellbutrin also had significantly fewer sexual problems than those taking Celexa or Remeron--a surprising result, in that Celexa and Remeron are generally assumed to be associated with minimal sexual dysfunction. In addition, the authors note that 70% of the patients they asked to participate in this study agreed to share information about their sexual function under antidepressant therapy, reinforcing the notion that patients are generally willing to discuss their sexual problems with a healthcare professional, if asked.

What to do?

Each year, according to the National Institute of Mental Health, more than 19 million adult Americans experience some form of depressive illness. Major depression alone is the single greatest cause of disability in the United States, with direct and indirect costs to society exceeding $30 billion a year. Clearly, we all have a stake in the successful treatment of depressive illness, and SSRIs represent a critically important advance toward this goal.

The latest research, however, suggests more attention should be paid to the sexual aspects of depression and its therapies. Unresolved sexual problems can make depression worse and lead patients to abandon otherwise successful treatments. Doctors need to speak more freely to their SSRI patients about sexual dysfunction related to drug therapy, and SSRI patients should be encouraged to volunteer information to their doctor about sexual side effects, especially since a wide range of options are available to help solve the problem without compromising the primary goal of managing the patient’s illness.