There are only three oral drugs approved by the FDA to treat erectile
dysfunction: Cialis, Levitra, and Viagra. All work by increasing the flow of
blood into the penis so that when a man is sexually stimulated, he can get an
erection.

What Are the Differences Between Cialis, Levitra, and Viagra?

Cialis, Levitra, and Viagra work by a similar mechanism to cause erections.
There are subtle differences in how long the drug works and how quickly it
works. Levitra works a little longer than Viagra. They both take effect in
about 30 minutes. With Levitra, the effects last for about 5 hours. With
Viagra, the effects last approximately 4 hours.

Cialis works a bit faster (within about 15 minutes), and the effects last
much longer — up to 36 hours in some cases.

If One of These Drugs Isn’t Effective for Erectile Dysfunction, Can I Try Another?

Yes, but because these drugs work the same way, it’s unlikely that you’ll
have success with one if you’ve failed to achieve an adequate erection with
another.

What Precautions Should I Take Before Taking One of These Drugs?

There are certain situations in which these drugs may not be safe to take.
Before taking them, tell your doctor:

• If you are allergic to any drugs, including Viagra or other ED
  medications.
• About any drug dysfunction erectile medication or nonprescription medications you are currently
  taking, including herbal and dietary supplements.
• If you are scheduled for surgery, including dental surgery.
• If you take nitroglycerin or a long-acting nitrate to treat chest pain. The
  combination of Cialis, Levitra or Viagra with these drugs can cause dangerously
  low blood pressure.
• If you take erectile dysfunction pill
  for blood pressure or prostate problems. The
  combination of Cialis or Levitra with these drugs can also cause dangerously
  low blood pressure.

In addition, always follow the directions on your prescription label
carefully and ask your doctor or pharmacist to explain any part that you do not
understand. Take these drugs exactly as directed. Do not take more or less or
take it more often than prescribed by your doctor. Do not take these drugs more
than once a day.

Who Should Not Take Cialis, Levitra or Viagra?

If you have suffered from a heart attack, stroke or life threatening
arrhythmia (irregular heart rate) within the last 6 months you should discuss
other options with your doctor. It is also advised to avoid these drugs if you
have ed pills
high or low blood pressure or if you experience chest pain
with sex.

What Are the Side Effects of Cialis, Levitra and Viagra?

Side effects are not common but they can occur. Side effects can
include:

• Headache
• Upset stomach or heartburn
• Flushing (feeling warm)
• Nasal congestion
• Changes in vision (color, glare)
• Back pain (with Cialis)

Call your doctor if you experience severe forms of these symptoms or if they
do not go away after 4-8 hours.

Warning

Call your doctor or seek emergency treatment immediately if you experience
any of the following symptoms:

• Rash
• Painful erection
• Prolonged erection (longer than 4 hours)
• Fainting
• Chest pain
• Itching or burning during urination

Stop taking these medications and call a doctor or health care provider
right away if you experience sudden or decreased vision loss in one or both
eyes. A rare vision problem called NAION has been reported by a few men using
these drugs. NAION (nonarteritic anterior ischemic optic neuropathy) causes a
sudden loss of eyesight because blood flow is blocked to the optic nerve.
People who have a higher chance for NAION include those who:

• Are over 50 years old
• Smoke
• Have heart disease
• Have diabetes
• Have high blood pressure
• Have high cholesterol
• Have certain eye problems

How Should These Drugs Be Stored?

These drugs should be kept in its original container and out of reach of
children. Store them away from excess heat and moisture (not in the bathroom).
Discard any medication that has expired or is no longer needed.

Reviewed by the doctors at the Glickman Urological
Institute at The Cleveland Clinic.