Since its introduction in 1998, sildenafil — better known by its trade name Viagra — has been one of the most popular prescription medications on the market. It was the first “as needed” pill treatment for erectile dysfunction (also called impotence ), a problem that may affect up to 30 million American men. Recently two other drugs — vardenafil (Levitra) and tadalafil (Cialis) — have joined sildenafil in a class of drugs known as phosphodiesterase type 5 inhibitors (PDE5 drugs). Although a number of other treatments are available, PDE5 drugs have the advantage of being simple, effective and generally safe. If you or your partner is thinking about using one of these drugs, the following information may help you decide if this treatment is right for you.
What are erectile dysfunction drugs?
Viagra is a prescription medication that helps men with erectile dysfunction to achieve and maintain an erection. It is taken as a pill, usually one hour before you anticipate engaging in sexual activity. Levitra and Cialis are similar drugs. They differ mainly in how quickly they work, and how long they remain active within the body.
How do they work?
A normal erection is more complicated than it may seem. During sexual arousal, the brain sends signals to the penis via nerves that travel through the spinal cord. These nerves trigger changes in blood vessels, which allow blood to flow into the penis but prevent the blood from draining out. The accumulation of blood in the penis causes the penis to enlarge and stiffen. After ejaculation, the vessels in the penis relax, and blood drains out. Any disease or injury that interferes with this complex process — such as damage to the blood vessels or nerves — may cause erectile dysfunction.
In most men, erectile dysfunction is caused by inadequate flow of blood into the penis. PDE5 drugs work by helping the blood vessels relax, which increases blood flow. They do not cause an erection without sexual stimulation, and the penis will return to its normal size and flaccid state after ejaculation. They also have no effect on sexual desire (libido) and do not change sensation in the penis.
Are they effective?
Yes, PDE5 drugs are very effective. In some studies, up to 70 percent of men had some improvement in erections after taking one of these drugs. PDE5 drugs appear to work in men regardless of why they have erectile dysfunction — including vascular disease, nerve problems and even psychological causes.
Do they work for everyone?
No. One in three men with mild to moderate erectile dysfunction do not respond to Viagra. Some men who do not respond to Viagra may have some effect with Levitra or Cialis. Men with more severe erectile dysfunction (severity is based on many factors, including frequency of erections, stiffness and sexual satisfaction) are less likely to respond to a PDE5 drug. This is particularly true if the cause is nerve damage, such as that associated with diabetes or certain types of prostate surgery. In addition, many men have a partial response to a PDE5 drug that does not totally restore normal erections.
Can women take them?
Currently, the U.S. Food and Drug Administration (FDA) has not approved Viagra, Levitra or Cialis for use in women. Preliminary studies suggest that these medications are safe for women, although their effectiveness in treating most female sexual problems is unclear. Some studies suggest PDE5 drugs may improve the sexual response in women who have impaired orgasm as a side effect of certain types of antidepressant medications. Other studies suggest they may also help some women who have difficulty with desire or arousal. However, more studies are needed to help us understand if and when Viagra and related drugs should be used by women.
Are they safe?
This issue has raised considerable concern. Within the first year of Viagra’s release, the FDA documented the deaths of 130 men who were taking the drug. Most of these men died of heart disease. Some of them were taking nitrates (nitroglycerin), a type of heart medication that is known to have devastating side effects when combined with Viagra. In other men, it is unclear whether Viagra contributed to their death. One theory is that heart problems may be triggered by vigorous sexual activity rather than by Viagra itself.
Subsequent studies suggest that, in fact, men with stable heart disease may safely use Viagra and related drugs. However, PDE5 drugs should never be combined with nitroglycerin or other forms of nitrates (such as isosorbide). This can produce a life-threatening drop in blood pressure, even in men without heart problems. If you seek medical attention for chest pain and have taken Viagra, Cialis or Levitra within the past 24 hours, be sure to inform your doctor of this fact. A serious drop in blood pressure may also occur if PDE5 drugs are mixed with alpha-blocker drugs such tamsulosin (Flomax) or doxazosin (Cardura), which are commonly prescribed for prostate problems, and street drugs known as “poppers” (amyl nitrate or butyl nitrate). Viagra and related drugs should also probably not be taken by men with the following medical problems:
- Heart attack or stroke within six months
- Unstable heart disease or heart failure
- High blood pressure that is controlled only with multiple medications
- Very high or very low blood pressure
- Liver or kidney disease
- Retinitis pigmentosa (a rare eye disorder)
Men who have multiple risk factors for heart disease (high blood pressure, high cholesterol, diabetes) and lead a sedentary lifestyle should consider having a stress test if they anticipate resuming vigorous sexual activity after starting any treatment for impotence.
If you are unsure whether Viagra or a related drug is safe for you, be sure to discuss this frankly with your doctor. PDE5 drugs can also interact with multiple medications other than nitrates, so it is important to provide your doctor with an accurate list of the medications you take.
What are the side effects?
The most common side effects are headaches, lightheadedness and facial flushing, which occur in about 15% of men. Other reactions include nasal congestion, indigestion, and back pain. Blue-tinged vision is even less common. In almost every case, these side effects are mild and temporary or fleeting.
The use of PDE5 drugs is associated with a rare condition called Nonarteritic anterior ischemic optic neuropathy (NAION). It is a poorly understood disorder that can cause blindness. Fortunately, the number of cases is very small in relation to the millions of men who have used ED pills successfully. It’s not clear that there is a cause-and-effect relationship between ED pills and NAION.
Another rare side effect is a prolonged painful erection (priapism). If an erection lasts more than 4 hours, you need emergency care.
Most recently, a few men who have taken a PDE5 drug have developed sudden hearing loss. Similar to NAION, it is not clear these drugs are the actual cause of the hearing problem.
Can these drugs be abused?
PDE5 drugs are not habit forming or addictive. They do not increase sexual desire or sexual enjoyment, other than by helping a man to achieve and maintain an erection. There is concern that Viagra, Levitra and Cialis could be misused as “performance enhancers” by some men who do not have erectile dysfunction. However, there is no reason to believe that these medications are unsafe when used in this manner, as long as they are taken in the recommended dosage and with the usual precautions.
How do I get one of these drugs?
Men with erectile dysfunction who would like to try Viagra, Levitra or Cialis should discuss this with their doctor, who can prescribe one of these drugs. In most cases, your doctor will want to review your medical history, perform a physical examination and possibly order blood tests to measure such things as hormone levels.
Erectile dysfunction may be caused by a number of different medical and psychological conditions. Some of these conditions also increase the risk for heart attack and stroke, so it is important that your doctor evaluate you carefully before prescribing a PDE5 drug. In some cases, your doctor may suggest an alternative treatment, such as testosterone injections or psychotherapy.
There is some concern that Viagra and related drugs are such effective treatments that they will be used as a “cure-all” and important treatable causes of impotence will be overlooked. Thus, a thorough evaluation is necessary.
How are the drugs taken?
Viagra should be taken on an empty stomach. The medication takes about one hour to work. The usual dose is 50 milligrams. Some men get good results with half that dose, whereas others need a higher dose. The maximum dose is generally considered to be 100 milligrams. Viagra should work for about 4 hours.
Levitra is very similar to Viagra. It takes about 60 minutes to work and lasts about 4 hours. It can be taken on either an empty or full stomach. The usual starting dose is 10 milligrams. Some men respond to as little as 2.5 milligrams, while others need 20 milligrams. It should not be taken more than once per day.
Cialis works a little faster than Viagra or Levitra (30 vs. 60 minutes) and last quite while longer — up to 36 hours. It should not be taken more than once per day. The usual starting dose is 10 milligrams. Some men respond to 5 milligrams, while others need 20 milligrams. Lower and less frequent doses are recommended for men who have liver or kidney problems, or who are taking certain other medications that interact with Cialis.
How will these medications affect my sex life?
Some couples who have not had sexual intercourse for many years are able to resume doing so with the help of drugs like Viagra, Levitra or Cialis. Usually, this is a positive experience, and both members of a couple are able to enjoy greater sexual satisfaction. However, some women who have grown accustomed to not having intercourse may experience discomfort or anxiety when intercourse is resumed. It is thus important for couples to communicate about sexual matters. Men who would like to resume intercourse after a period of abstinence should be sure to discuss this with their partner.
Are alternative treatments available?
Yes. Although few other treatments for erectile dysfunction are as easy to use as the PDE5 drugs, alternatives are definitely available. Some of these treatments — such as a penile implant — may help men who don’t respond to pill forms of treatment. In addition, new treatments are in development, including faster-acting pills and creams applied directly to the penis.