10 Surprising Antidepressant Facts

Antidepressants Make Shrimp Act Crazy

You've probably heard about all the prescription meds in our water supply. Turns out Prozac in public waters makes shrimp act nutty—and not in a good way.

Seems that the active ingredient in antidepressants like Prozac boosts serotonin in the shrimps' nervous system and make them wiggle away from safe, dark waters toward the light, where they're more likely to be devoured by predators.

And because researchers don't think Prozac has the same mood-elevating effect in shrimp as it does in people, the crustaceans don't even get to die happy.

All Antidepressants Are Equally Effective

If your doctor is pushing one type of happy pill on you, beware: There is no evidence to suggest that one antidepressant is more effective than another at making you feel better, according to guidelines from the American College of Physicians.

Cost and side effects—including nausea and weight gain—do vary, however, and should play a role when choosing a medication.

Their Cost Varies Wildly

Although the efficacy of antidepressants is very similar, the price is not.

A monthly supply of duloxetine (Cymbalta)—a drug that is still patent protected—costs about $300, according to figures compiled by Consumer Reports; an equivalent supply of a generic version of fluoxetine (Prozac) runs about $30 a month.

Gregory Simon, MD, a psychiatrist and researcher at the Kaiser Permanente Washington Health Research Institute, in Seattle, says, "I can say with 100% certainty: The more expensive one is no better."

Antidepressants Are Good (And Bad) For Your Sex Life

While the libido-deflating effects of a class of antidepressants called selective serotonin reuptake inhibitors (SSRIs) have been well documented, another side effect hasn't been: Doctors are increasingly prescribing SSRIs off-label to treat men for premature ejaculation based on the medication's side effect of delayed ejaculation.

A 2006 study found that men who took the SSRI dapoxetine (Priligy) one to three hours before intercourse had ejaculation times of over three minutes, on average, compared with less than two for the placebo group.

Some Men's Libidos Never Bounce Back

Low libido, erectile dysfunction, decreased genital sensitivity, and difficulties reaching orgasm are some of the sexual side effects reported by patients taking SSRIs.

Doctors always assumed these problems would resolve themselves once the patient stopped taking the medication, but several small studies—and a growing group of patients—say the effects can continue indefinitely.

Antidepressants May Damage Sperm

In a 2009 study, more than 40 percent of the 35 healthy participants who took the SSRI paroxetine (Paxil) for four weeks had sperm with fragmented DNA, which could affect fertility.

Although the men's sperm returned to normal within a month of going off paroxetine, men seeking to conceive should check with their doctors about antidepressants.

They May Be Bad for the Bones

Some researchers have found that SSRIs are associated with lower bone density and more hip fractures in older people, suggesting that people taking SSRIs have regular osteoporosis screenings.

However, other studies have not found this connection, prompting some researchers to say that more studies are needed to determine if SSRIs really increase the risk of low bone density and fractures.

Antidepressants Could Help Fibromyalgia

The use of antidepressants—including SSRIs like Prozac and especially older antidepressants like tricyclics and tetracyclics—is associated with less pain, fewer sleep disturbances, and less depressed moods in people who suffer from fibromyalgia, according to a study published in the Journal of the American Medical Association.

In fact, two of the three drugs approved by the FDA for fibromyalgia are antidepressants.

Antidepressants Take Weeks to Work

Some pills have a quick effect. However, it can take up to eight weeks for SSRIs to build up in the brain and body to the point they can affect mood, psychiatrists say.

This phenomenon is known as the "Prozac lag."

Which is why, if you're taking an SSRI and it doesn't seem to be working, you may need to make sure you have given it enough time.

Puppies and Polar Bears Are on Prozac

While no one knows how many pets are on Prozac, Americans spend an estimated $15 million a year on behavioral medication for their cats and dogs.

In 2007, Eli Lilly, the maker of Prozac, launched Reconcile, a chewable form of its drug, for canine separation anxiety.

Now even zoo animals are on antidepressants, for everything from aggression to obsessive-compulsive disorder.