I recently appeared on the television show The Doctors to answer questions about the development of a male contraceptive pill.

A lot of interest has been generated because researchers have focused their efforts over the past several years on developing a male contraceptive similar to the female pill. Although this research has been going on for decades, the momentum seems to be increasing, and now scientists have potentially found an effective solution. The big question is, will guys take the pill (and will ladies trust them)?

Current efforts are focused on developing a pill that would block the function of vitamin A in the testes and, theoretically, reversibly turn off sperm production. After 50 years of work, researchers have learned that the conversion of vitamin A to retinoic acid in the testes can be blocked. The main concern is finding a way to block this conversion in the testes without affecting the function of vitamin A and retinoic acid in other tissues. Tests with mice have shown a 100 percent success rate.

Researchers have also found a hormonal-free way to prevent the testicles from producing sperm and are testing a drug that targets a particular protein that is critical for sperm production. The treatment is reversible—when mice were taken off the medication, they became fertile again.

In addition, there are two classes of drugs on the market that cause men to experience retrograde (backward) ejaculation, which, in essence, keeps men from emitting semen during orgasm. However, it is impractical to use these drugs in clinical practice because one is an antihypertensive and the other is an antipsychotic medication. Without modification, they would adversely affect blood pressure and mood.

Hormones delivered by implants, injections, gels, or pills have a profound effect on sperm production. Testosterone suppresses the production of sperm by working directly on the testicles, and progestin sends signals from the brain to the testes to stop producing testosterone. The long-term effects of these medicines are unknown, but current knowledge suggests that prolonged use could increase the risk of heart disease and prostate cancer.

A researcher in India is developing a method called RISUG (reversible inhibition of sperm under guidance), in which a polymer is injected into the vas deferens and blocks sperm transport. According to the developer, the procedure is reversible. RISUG does require a small surgical incision in the scrotum to access the vas deferens. In my judgment, this option does not seem any better than a vasectomy, but the jury is still out. The procedure is now in late phase 3 clinical trials in India.

Remember, no contraceptive measure is 100 percent effective—not even hysterectomy. (Abdominal pregnancies can occur even after a total abdominal hysterectomy.) RISUG may be a promising means of birth control for males, but it is too early to draw any conclusions. The current media hype is unwarranted. Science will have to run its course and complete well-designed clinical trials before this, or any other, method can be recommended.

There is no question that the true need for a male contraceptive pill is compelling. Men produce about 1,000 sperm a second. At the end of the day, the only effective methods of male contraceptives are vasectomies (successfully reversible in greater than 95 percent of cases), condoms, and the tried and true method of “keep your zipper up!”

Dudley S. Danoff, MD, FACS is the attending urologic surgeon and founder/president of the Cedars-Sinai Medical Center Tower Urology Group in Los Angeles, California. He is the author of Penis Power: The Ultimate Guide To Male Sexual Health (Del Monaco Press, 2011) and Superpotency (Warner Books).

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