Viagra, Cialis, Levitra, and Stendra are popular drugs for treating the symptoms of erectile dysfunction.

They all have approval from the United States Food and Drug Administration (FDA), and they have the same function, but there are some differences between them.

It is important to understand these differences in order to make the best choice about which to choose.

cialis and viagra tabletsShare on Pinterest
Cialis and Viagra are PDE5 inhibitors that help to relax the muscles and increase blood flow. Other options are Levitra and Stendra.

Viagra is the brand name for the drug sildenafil, Cialis is the brand name for tadalafil, Levitra is the brand name for vardenafil, and Stendra is the brand name for avanafil.

The drugs all work in a similar way.

They are all PDE5 inhibitors. This means they help to relax the muscles and increase blood flow to the body.

This makes it easier for blood to get into the penis, and it allows people with erectile dysfunction (ED) to experience a lasting erection during sexual activity.

The drugs act relatively quickly. Manufacturers of PDE5 inhibitors recommend taking the pill at least 30 minutes to 1 hour before sexual stimulation, but the timing depends on the drug.

How long the effect of each drug lasts is one of the key differences between them:

  • Viagra is a drug that people use only when they need it. A person takes the drug 30 minutes to 1 hour before sexual activity, and the effects typically last for 3-5 hours.
  • Levitra may start working faster than Viagra, but it lasts for about the same amount of time.
  • The effect of a similar dose of Cialis may last up to 36 hours. For this reason, people looking for a long-lasting drug may choose Cialis.
  • Depending on the dose, Stendra will be effective after 15–30 minutes, and research shows it is effective for up to 6 hours.

Viagra, Cialis, Levitra, and Stendra all come from the same class of chemicals, and they have many similar side effects and interactions.

For instance, manufacturers recommend not taking PDE5 inhibitors with grapefruit or grapefruit juice, because the fruit may affect how the drugs work. Nitrates will also interact with these drugs, so people should not use them together.

There are some drug-specific side effects to be aware of, however.


The side effects include:

  • headaches
  • stomach pain
  • facial flushing
  • congestion
  • nausea or diarrhea
  • color blindness
  • blurred vision

Interactions and warnings

Interactions with Viagra do occur, and it is important for people to be aware of them before choosing a medication for ED. Any drugs for pulmonary hypertension may also interact with Viagra, causing blood pressure to drop to unsafe levels.

A recent study in JAMA Internal Medicine has suggested that Viagra could increase the risk of skin cancer. The study found that 3.7 percent of skin cancer cases in men who used the drug sildenafil might have been prevented by not taking it.


The side effects include:

  • headaches
  • facial flushing
  • low blood pressure
  • congestion
  • dizziness
  • chest pain

Interactions and warnings

Cialis may have some more serious side effects. People should not use it with guanylate cyclase stimulators or blood pressure medications, as this combination can trigger an unsafe dip in blood pressure.

A person who is taking Cialis and has prostate problems should avoid prescription alpha-blockers, as Cialis serves the same function. It will be like an additional dose.

People should also avoid certain antifungal medications and antibiotics when taking Cialis.

Anybody who is considering taking medications such as Cialis for ED should always involve their doctor in the decision.

The doctor may ask if the person has a history of any of the following:

  • heart problems
  • stroke
  • liver or kidney problems
  • stomach ulcers
  • abnormal penis shape
  • blood cell problems like sickle cell anemia

All of these conditions may affect the doctor’s decision to prescribe Cialis.


Share on Pinterest
People who may have a weak heart should avoid Levitra.

The side effects of Levitra include:

Interactions and warnings

If a doctor has told a person to avoid sexual activity due to health problems, they should avoid Levitra.

Sexual activity can put extra strain on the heart, especially if it is already weak from heart disease.

As with Cialis, a person should not use Levitra with:

  • guanylate cyclase stimulators or blood pressure medications, as these can cause an unsafe dip in blood pressure that can lead to fainting
  • alpha-blockers for prostate problems
  • certain antifungal medications and antibiotics

A doctor may ask a person if they have a history of any of the following:

  • heart problems
  • stroke
  • hearing problems
  • retinitis pigmentosa, an inherited eye condition
  • liver or kidney problems
  • stomach ulcers
  • abnormal penis shape
  • blood cell problems, such as sickle cell anemia

All of these conditions may affect a doctor’s decision to prescribe Levitra. People who are taking drugs to treat an abnormal heartbeat should also avoid taking Levitra.


The manufacturers of Stendra claim that it has a low rate of side effects.

However, like the other treatments for ED, there is a risk of adverse effects, including:

  • a headache
  • flushing
  • a stuffy or runny nose
  • a sore throat
  • back pain
  • vision problems, including possible sudden vision loss in one or both eyes
  • hearing problems, including a decrease or loss of hearing and tinnitus
  • low blood pressure
  • priapism, an erection that will not go away

A person should seek medical treatment if they experience:

  • vision or hearing loss
  • an erection that does not go away after 4 hours

Interactions and warnings

People should not use Stendra if they have or have had:

  • heart problems or heart surgery
  • pulmonary hypertension
  • low or high blood pressure
  • a deformed penis
  • a stroke
  • severe vision loss
  • bleeding problems
  • a stomach ulcer
  • kidney or liver problems

Anyone with any kind of health condition should speak to a doctor before taking Stendra or any of these medications.

A person should not take Stendra with the following drugs:

  • any type of nitrate
  • guanylate cyclase stimulators, such as riociguat (Adempas)
  • HIV protease inhibitors, such as ritonavir (Norvir)
  • some antifungal medication, such as ketoconazole (Nizoral)
  • some antibiotics such as clarithromycin (Biaxin)
  • alpha-blockers and other medications for blood pressure
  • other treatments for ED

People can take Stendra with or without food and with up to three servings of alcohol. It is important not to drink more than three alcoholic drinks, for example, three glasses of wine or three measures of whiskey, as this can lead to adverse effects.

When to see a doctor

All four medications may sometimes cause priapism, an erection that will not go away. If a person experiences an erection lasts for more than 4 hours, they should seek medical attention to avoid lasting damage.

In rare cases, these drugs can cause serious side effects, including sudden loss of vision in one or both eyes or sudden hearing loss. If a person experiences these symptoms, they should stop taking the drug immediately and call their doctor.

The other thing a person might consider is the cost and availability of each of these drugs. Some drugs have been around longer and may be more widely available than others.

Generic versions of Viagra, Cialis, and Levitra have approval from the FDA. These may be cheaper than brand-name drugs.


Viagra has been available since 1998 and is possibly the best-known drug for ED in the world. Its use in the U.S. is widespread, and most pharmacies sell it.


Cialis has been on the market since 2003. It is widely available and may be a cheaper option than Viagra.


Levitra received approval in 2003, and is available in most pharmacies in the U.S. There is a generic version, but it is not widely available.


Stendra received FDA approval in 2012 and is widely available in the U.S.

Every person is different, and a drug that suits one person may not suit another.

Share on Pinterest
A doctor or pharmacist can help you choose a suitable option.

Cialis is the only drug of the four that has approval for use by people with benign prostatic hyperplasia (BPH) or enlarged prostate. People with both ED and BPH should consider Cialis as their treatment option. Cialis also helps to improve urine flow.

A person can take Cialis every day to keep the body ready for sexual stimulation at any time. This allows for some sexual freedom that may be missing with the other options.

Viagra or Levitra may be better for people who do not engage regularly in sexual activity and would rather take one pill each time they plan on having sex.

Stendra does not have any significant advantages.

Personal reasons may also guide a choice. Each body reacts to medications differently. Side effects vary between people, and the potential side effects may help an individual to decide which drug suits them best. For instance, if one drug causes nausea, they might consider another drug.

Viagra, Levitra, Cialis, and Stendra will not cure ED, but they may provide relief from its symptoms.

There are many side effects and interactions to consider, but, with the right choice and correct use, studies show that these drugs can help a person to overcome ED and engage in sexual activity.

It is worth remembering, meanwhile, that none of these drugs will provide sexual stimulation. The person will need stimulation in order to have an erection.

The only way to know which drug is best for you may be through trial and error. People should work directly with a doctor to track side effects and decide which drug is their best treatment option.