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Viagra vs. Cialis: A detailed guide

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CostGenerics or biosimilarsUsesDosageSide effectsFAQWarningsWhat to ask
Viagra (sildenafil) and Cialis (tadalafil) are prescription drugs used to treat erectile dysfunction. Both of these medications come as tablets you’ll take by mouth, but their dosages differ.
Medically reviewed by Christina Bookwalter PharmD, MS MEd, BCPS, BCACP
Updated on

This article explains how Viagra and Cialis are similar and different. You can view detailed articles about Viagra and Cialis if you’d like more information about these drugs.

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Cost of Viagra and Cialis

As with the cost of other medications, the cost of Viagra and Cialis can vary. Their price may be affected by:

  • whether they’re covered by health insurance, if you have coverage
  • the pharmacy they’re purchased from
  • the quantity of tablets you’re prescribed

Coupons and cost savings

To view drug prices when Optum Perks coupons are applied, see this coupon page for Viagra and this coupon page for Cialis. You can also check with your doctor, pharmacist, or insurance provider.

The options described in this article may also help you save on your prescription.

Download the free Optum Perks Discount Card to save up to 80% on some prescription medications.

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Note: Optum Perks coupons cannot be used with insurance copays or benefits.

Generic versions

Below is information about whether Viagra or Cialis is available in a generic version.

A generic medication is an identical copy of the active ingredient in a brand-name medication. An active ingredient is what makes medication work. Generics usually cost less than brand-name drugs. And they’re believed to be as safe and effective as the brand-name versions.

Here’s a summary about generics of Viagra and Cialis:

 ViagraCialis
Active ingredientsildenafiltadalafil
Available as a genericyes yes

If your doctor prescribed Viagra or Cialis, but you’d like to know about taking its generic version, let your doctor or pharmacist know. They can help determine whether the generic version is right for you.

Uses of Viagra and Cialis

Here’s a summary of Viagra’s and Cialis’ approved uses:

 ViagraCialis
Approved useserectile dysfunction (ED) • ED
• signs and symptoms of benign prostatic hyperplasia (BPH)
• both ED and signs and symptoms of BPH
Prescribed toadultsadults

Cialis may sometimes be used with finasteride to start treatment for BPH. For this use, doctors may not prescribe Cialis with finasteride longer than 26 weeks.

If you’d like to know more about taking either medication for your condition, ask your doctor. They can recommend whether Viagra or Cialis are options to consider.

Dosage of Viagra and Cialis

Below is dosage information for the condition that both Viagra and Cialis are prescribed to treat. To find detailed dosage information for all conditions that Viagra and Cialis treat, see these articles about Viagra dosage and Cialis dosage.

Below are dosages provided by the drugmakers of Viagra and Cialis. If your doctor prescribes either medication, you should follow the dosage they prescribe. They’ll advise the dosage that’s best for your condition. Do not adjust your dosage without first talking with your doctor.

Viagra’s dosage

Below is a summary of Viagra’s recommended dosage in adults. Strength is measured in milligrams (mg).

ConditionHow it’s takenRecommended dosageMaximum frequency
ED in adultsoral tablet50 mg taken as needed about 1 hour before sexual activity, but it may be taken 30 minutes to 4 hours before sexual activity.

Your doctor may increase your dosage to 100 mg or decrease it to 25 mg. This is based on how well Viagra works for you or how well you tolerate it.
once per day

Cialis’ dosage

Below is a summary of Cialis’ recommended dosages in adults. Strength is measured in milligrams (mg).

ConditionHow it’s takenRecommended dosageMaximum frequency
ED in adultsoral tablet • 10 mg taken as needed before sexual activity. Your doctor may increase your dosage to 20 mg or decrease it to 5 mg based on how well Cialis works for you or how well you tolerate it.
• 2.5 mg taken once per day, everyday without regard to timing of sexual activity. Your doctor may increase your dosage to 5 mg once per day based on how well Cialis works for you or how well you tolerate it
once per day

Side effects of Viagra and Cialis

Viagra and Cialis may cause mild or serious side effects. Some of the more common mild side effects of each drug are listed below. Serious side effects of Viagra and Cialis are also listed.

Keep in mind that your side effects may differ from those listed below. They can vary based on your overall health, any other medications you take, and your age.

This article doesn’t include all possible side effects of these medications. To find more information, you can view the prescribing information for Viagra and Cialis. You can also check out these articles about Viagra side effects and Cialis side effects.

Mild side effects

Below are some of the mild side effects reported with Viagra and Cialis:

 ViagraCialis
headache
indigestion
flushing (temporary warmth, redness, or deepening of skin color)
back pain
muscle aches
mild allergic reaction

Serious side effects

Below are serious side effects reported with Viagra and Cialis:

 ViagraCialis
sudden loss of vision due to possible optic nerve damage ✓ 
priapism (long lasting erection)✓ 
sudden decrease or loss of hearing
low blood pressure
heart-related side effects, including heart attack
serious allergic reaction✓ 

With a lot of drugs, serious side effects are possible, but they’re not common. If you have serious side effects from Viagra or Cialis, call your doctor right away. If your symptoms are severe or you’re having a medical emergency, call 911 or a local emergency number.

Questions about Viagra and Cialis

Below, you’ll find answers to some common questions about Viagra and Cialis.

How does Viagra or Cialis compare with Levitra?

Like Viagra and Cialis, Levitra is an oral tablet approved to treat ED in adults. But brand-name Levitra is no longer available. The generic version of Levitra, vardenafil oral tablet, is available. Viagra, Cialis, and vardenafil have some similarities and differences:

  • Viagra and vardenafil are only approved to treat ED. Cialis is also approved to treat the symptoms of BPH.
  • Viagra, Cialis, and vardenafil all belong to a group of drugs known as phosphodiesterase 5 (PDE5) inhibitors. They all work in a similar way to treat ED and they have similar side effects and warnings.
  • The dosages of Viagra, Cialis, and vardenafil are different. Viagra or vardenafil are taken about 1 hour before sexual activity. But Viagra may be taken 30 minutes to 4 hours before sexual activity. Vardenafil doesn’t have this dosing flexibility. When Cialis is taken as needed, it may be taken any time before sexual activity.
  • The costs of Viagra, Cialis, and vardenafil may differ, especially since vardenafil is a generic drug. Generic drugs usually cost less than brand-name drugs.

Talk with your doctor or pharmacist if you have questions about how Viagra, Cialis, and vardenafil compare.

Is it safe to take Viagra and Cialis together?

No, it’s not recommended to take Viagra and Cialis together. Viagra and Cialis both belong to a group of drugs known as PDE5 inhibitors. They work in a similar way to treat ED and they have similar side effects and warnings.

Taking both of these drugs together may increase your risk of side effects, including low blood pressure. (For more information about how these drugs’ side effects compare, see the “Side effects of Viagra and Cialis” section above.)

If you have questions about how to take Viagra or Cialis, talk with your doctor or pharmacist. They can recommend the best way to take either drug. Or they can discuss other treatment options if one drug isn’t working well for your condition.

Between Viagra and Cialis, is one a better treatment for ED?

Doctors may prescribe either Viagra or Cialis to treat ED. In studies, Viagra and Cialis were both effective for this purpose.

That said, these medications differ in some ways. For instance, they have different dosages, strengths, approved uses, and costs.

Keep in mind that your results from taking Viagra or Cialis may differ from those seen in studies.

Your doctor can help determine whether one option is better for your condition. They’ll recommend this based on your specific needs and health factors. Talk with your doctor if you’d like to learn more about which drug is right for you.

Warnings for Viagra and Cialis

Some medications may not be recommended for you if you have certain factors affecting your health. These are referred to as a drug’s warnings.

Some people should not take Viagra or Cialis, and others should take either medication with caution.

Before taking either medication, talk with your doctor about your health conditions, past surgeries, and any medications you take. Your doctor can recommend whether either drug is safe for you.

Warnings for Viagra and Cialis are summarized in the table below:

 ViagraCialis
taking certain other medications, including nitrate drugs or alpha-blockers✓ 
certain heart problems, such as heart disease
pulmonary hypertension
high or low blood pressure
priapism
irregular penis shape, such as Peyronie’s disease
blood cell problems
bleeding problems
stomach ulcers
severe vision loss or optic nerve damage 
retinitis pigmentosa
sudden decrease or loss of hearing
consuming large amounts of alcohol
kidney or liver problems
allergic reaction to either drug or any of their ingredients✓ 

You can view more detailed articles about Viagra and Cialis if you’d like to know more about warnings for these drugs. You can also view the prescribing information for Viagra and Cialis.

What to ask a doctor

If you’re trying to decide whether Viagra or Cialis is better for you, talk with your doctor. They can recommend the best option.

Here’s a list of questions you may want to ask your doctor:

  • Is there a reason why Cialis might be better for my condition than Viagra?
  • Does Viagra or Cialis interact with any other drugs I’m taking?
  • How does Viagra or Cialis compare with other drugs for ED?

Disclaimer: Optum Perks has made every effort to make certain that all information is factually correct, comprehensive, and up to date. However, this article should not be used as a substitute for the knowledge and expertise of a licensed healthcare professional. You should always consult your doctor or another healthcare professional before taking any medication. The drug information contained herein is subject to change and is not intended to cover all possible uses, directions, precautions, warnings, drug interactions, allergic reactions, or adverse effects. The absence of warnings or other information for a given drug does not indicate that the drug or drug combination is safe, effective, or appropriate for all patients or all specific uses.

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