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What to Know About Generic Viagra & Cialis

By Sarah Malka, MD bool(true)
Medically reviewed
April 13, 2021

Viagra and Cialis have helped millions of men with erectile dysfunction (a.k.a. impotence) achieve firmer erections and improved sexual experiences. Still, not everyone can afford these prescription medications. 

That doesn’t mean you have to choose between going broke or having an unsatisfying sex life. Generic Viagra, called sildenafil, and generic Cialis, tadalafil, are cheaper alternatives that are as safe and effective as their famous counterparts.

Many people don’t realize that generic medications have the same active ingredients and provide the same benefits as their brand-name versions. So in this article, I’ll explain the differences and similarities between branded and generic ED medications, the side effects of generic Viagra and Cialis, and how to make sure the medication you buy online is safe.

What Is ED Medication?

There are four oral FDA-approved medications to treat erectile dysfunction: sildenafil (Viagra), tadalafil (Cialis), vardenafil (Levitra), and avanafil (Stendra).

All of these are phosphodiesterase-5 (PDE5) inhibitors. They work by blocking the enzyme PDE5, which results in an increase in another molecule (cyclic guanosine monophosphate, or cGMP) that causes muscles to relax.

That may seem counter to an erection, but you want the arteries in the penis to relax, because then more blood can flow into the penis—that’s what causes a penis to swell and become erect.

Sildenafil and tadalafil work the same way as Viagra and Cialis. But you cannot just pop a pill and expect an erection—you need sexual stimulation too. When you combine any of these ED medications with something that turns you on, it results in firmer, longer-lasting erections. 

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What’s the Difference Between Generic and Brand Name Medications? 

Generic and brand-name medications are bioequivalent to one another, meaning they are equally safe and effective. They have the same active ingredients in identical amounts and provide the same health benefits for the people who take them.

The only difference is their inactive ingredients and cost. Brand-name medications like Viagra and Cialis tend to be more expensive than their generic counterparts. 

Generic versions of brand-name medications exist because of the way prescription drugs are developed, trademarked, and marketed in the United States.

When a prescription drug company creates a new medication, they must pay for research and development, including animal and human testing, to ensure a drug is safe before it hits the market.

When the FDA approves a medication for patient use, they reward the company for taking on the expense of developing a new drug by giving it a patent on the pill. Currently, that means that for at least 20 years, the company is the only one that can sell the drug they created. 

To recoup their costs and maximize their profits, drug companies with a trademark medication usually brand it with a consumer-friendly name and spend money to market it to consumers. All of that translates to a higher prescription drug price when you get it from your pharmacy.

Once a patent expires, other drug companies can use the initial research and development results to create their own versions of the medication. Because they don’t have to spend so much money on testing, they can sell their drugs for less money.  

Viagra vs. Sildenafil

Viagra is the original medication that Pfizer researched and developed; sildenafil is the generic form of Viagra.

The exact cost of sildenafil depends on your dosage, insurance, and pharmacy. (At K Health, it starts at $1.80 per 25-mg pill.)

However, the price can be 10 times less than that of Viagra, and both medications work equally well.

Cialis vs. Tadalafil

Cialis is the original drug that Lilly ICOS developed; tadalafil is the generic form of Cialis.

Depending on the dosage, pharmacy, and your insurance, the cost of tadalafil is roughly half of Cialis’s. (At K Health, tadalafil starts at less than $1 per 5-mg pill.)

Here too, generic tadalafil is equally effective as Cialis at treating ED.

When Did Generic Viagra and Cialis Become Available?

The FDA approved Viagra for patient use in 1998 and Cialis in 2003.

Pfizer began selling generic sildenafil in 2017, and other prescription drug companies could do the same once Pfizer’s patent expired in 2020.

Similarly, when Lilly ICOS’s patent on Cialis expired in 2018, other pharmaceutical companies stepped in to create generic tadalafil. 

Today, several prescription drug companies sell generic sildenafil and generic tadalafil.

What Do Generic Viagra and Cialis Look Like?

When it first hit the market, many referred to Viagra as “the little blue pill” because of its distinct color and diamond shape, as pictured above.

Generic versions of Viagra, however, come in a variety of shapes, sizes, and colors. That’s because although they must contain the same active ingredients as Viagra, the FDA requires that generic drugs look different enough for consumers not to confuse them with their brand-name versions. 

Generic Cialis is often white instead of blue and can come in a round or oval shape instead of a diamond.

The difference between tadalafil and Cialis is the shape. Both pills are yellow, but Cialis is always oval-shaped, while tadalafil can be oval or circle-shaped, depending on the manufacturer. 

Are There Side Effects of Generic Viagra and Cialis?

Because they have the same active ingredients as Viagra and Cialis, generic forms of these medications risk the same side effects:

  • Flushing or warm skin
  • Indigestion
  • Nausea
  • Diarrhea
  • Headache
  • Muscle aches
  • Nasal congestion or bloody nose 

Occasionally, sildenafil and tadalafil can cause more severe side effects, including: 

  • Blurred vision
  • Light sensitivity
  • Decreased color vision or difficulties visually differentiating between colors 
  • Buzzing or ringing in the ears
  • Confusion
  • Lightheadedness 
  • Unusual weakness or fatigue 

Do not take more medication than you are prescribed, as doing so can increase your chances of developing severe side effects. If you take ED medications and experience any of the following, immediately call your doctor or go to your nearest emergency room.

  • Fainting
  • Difficulty breathing 
  • Sudden changes in vision
  • Sudden changes in hearing
  • Swelling in the hands, feet, ankles, or any part of the face
  • Heart attack symptoms
  • Seizure 
  • A painful erection or an erection that lasts more than four hours 

People with heart problems, including those who have experienced a heart attack, stroke, irregular heartbeat, or low blood pressure, should talk to their doctor before taking any erectile dysfunction medication.

Sildenafil, tadalafil, and other ED drugs can cause complications for cardiovascular patients and interact poorly with heart and blood pressure medications.

If you take sildenafil or tadalafil and feel chest pain, nausea, dizziness, or other heart attack symptoms, seek medical attention immediately. When you do, tell the healthcare provider when your last dose was.

ED medications can also cause vision problems in people with certain pre-existing eye conditions. If you have retinitis pigmentosa or non-arteritic anterior ischemic optic neuropathy (NAION), taking sildenafil or tadalafil may increase your risk of permanent vision impairment or blindness. Talk to your ophthalmologist before beginning any ED medication. 

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Beware of Counterfeit Viagra and Cialis

Illicit versions of PDE5 inhibitors like Viagra, Cialis, and their generic versions make up most of the counterfeit drugs on the market. Not only can the strength of these fake pills vary significantly from their FDA-approved counterparts, they also often contain additional unapproved ingredients that are hazardous to your health or haven’t been tested.

Most men exposed to counterfeit erectile dysfunction medications purchase them through the internet. You can find and buy brand-name and generic versions of FDA-approved ED medications online, but you have to be cautious.

  • Only buy from websites that require a doctor’s prescription and that have a pharmacist available to answer questions.
  • Only purchase from licensed online pharmacies.
  • Check that the pharmacy has a physical US address.

Also know that, because they’re prescription medications, you cannot buy sildenafil or tadalafil over the counter in the United States.

Get Generic Viagra or Cialis Online with K Health 

K Health provides a simple, accessible option for ED treatment. Chat with a doctor on your phone to determine whether you are experiencing ED. Your doctor will then prescribe you medication, which can be picked up at a local pharmacy or shipped discreetly directly to you.

Frequently Asked Questions

How much does generic Viagra cost?
The exact cost of generic Viagra (sildenafil) depends on your dosage, insurance, and pharmacy. However, people often save more than 50% when buying the generic version rather than the brand name.
When did Viagra go generic?
Pfizer (the maker of Viagra) began creating a generic form of the pill in 2017. When the patent on Viagra expired in 2020, several other pharmaceutical companies also started making sildenafil medications.
Is generic tadalafil as good as Cialis?
Generic tadalafil is considered bioequivalent to Cialis, meaning it contains the same ingredients and is equally beneficial and safe for people who have ED
Is generic sildenafil as good as Viagra?
Compared to Viagra, generic sildenafil is identically safe, effective, and beneficial for people living with erectile dysfunction.
Where can I buy generic Cialis?
Generic Cialis, or tadalafil, is available by prescription only. Once you have a prescription, you can purchase it from your neighborhood pharmacy or a licensed online pharmacy. Never buy erectile dysfunction medication if you do not have a prescription. You risk buying and taking dangerous counterfeit drugs.
Where can I buy generic sildenafil?
You can purchase generic sildenafil with a prescription from your local pharmacy or licensed online pharmacies. There is no such thing as over-the-counter generic sildenafil.
K Health articles are all written and reviewed by MDs, PhDs, NPs, or PharmDs and are for informational purposes only. This information does not constitute and should not be relied on for professional medical advice. Always talk to your doctor about the risks and benefits of any treatment.

Sarah Malka, MD

Dr. Sarah Malka is a board certified emergency medicine physician with K Health. She completed her residency at Harvard Medical School.