Comparing Viagra, Levitra, and Cialis
The Basics
| Brand name | Cialis | Levitra | Viagra |
| Drug name | Tadalafil | Vardenafil | Sildenafil |
| Generic version | yes | no (soon) | yes |
| Strengths |
- 2.5 mg - 5 mg - 10 mg - 20 mg |
- 2.5 mg - 5 mg - 10 mg - 20 mg |
|
| When to take |
30-60 mins before sex or once daily | 30-60 mins before sex |
30-60 mins before sex |
| How long it lasts | up to 36 hours | up to 8 hours | up to 8 hours |
Be sure to take this drug exactly as your doctor tells you to. If you have questions or concerns, talk with your doctor.
Drug features
Cialis, Levitra, and Viagra are all in a class of drugs called PDE-5 inhibitors. These drugs work by blocking an enzyme called phosphodiesterase type 5. They also boost a chemical in your body called nitric oxide. This action encourages the muscles in your penis to relax. Relaxed muscles allow blood to flow freely so that when you’re aroused, you can get an erection. It also helps you maintain the erection long enough to have sex.
Levitra and Viagra stay in your bloodstream for about four to six hours. Cialis remains in your bloodstream for 17 to 18 hours or longer. The length of time a drug stays in your system may be important if you’re taking other medications.
Side Effects
The chart below compares the side effects of these drugs.
| Side effect | Cialis | Levitra | Viagra |
| stuffy or runny nose | x | x | x |
| headache | x | x | x |
| upset stomach | x | x | x |
| changes in vision | x | x | |
| flushing | x | x | |
| back pain | x | ||
| muscle aches | x | ||
| priapism (an erection that won’t go away) | x | x | x |
| sudden cardiac arrest and death | x | x | x |
Tell your doctor if you have any side effects that linger and don’t go away on their own. If you have an erection that lasts longer than four hours, call your doctor right away.
Drug interactions
Each drug comes with the chance of drug interactions. Since PDE-5 inhibitors work on the body in similar ways, Cialis, Levitra, and Viagra come with similar interactions.
All three of these drugs interact with nitrates. They also all interact with blood pressure drugs such as alpha-blockers. For Cialis, these also include the drugs bendrofluazine, enalapril, and metoprolol. For Viagra, these also include the blood pressure drug amlodipine.
Viagra also interacts with the drug ritonavir.
Cialis can also interact with alcohol. Drinking alcohol with Cialis can cause low blood pressure when you stand up from a sitting or lying position. This may result in dizziness or a headache. To learn more, read more about the effects of mixing Cialis and alcohol.
Levitra and Viagra do not seem to cause low blood pressure when taken with alcohol. However, alcohol may interfere with your ability to get an erection, even while you’re taking any of these drugs.