The array of erectile dysfunction medications on the market these days can present a challenge for guys just trying to understand what, where, and how they should begin with an E.D. medication.

The first thing to understand is that all of the FDA-approved ED meds have demonstrated great safety and effectiveness in clinical trials and have been used by millions of men for over twenty years! And, the best erectile dysfunction medications are not available over-the-counter (OTC) .

Viagra® (sildenafil) and Cialis® (tadalafil) are the two most popular options for good reason.

Do Viagra And Cialis Work The Same Way?

Viagra is the brand name for sildenafil citrate, a drug discovered by chemists at Pfizer while seeking a treatment for pulmonary hypertension. Viagra is a PDE5 inhibitor that helps to relax the smooth muscles in the penis, promote blood flow, and help to create strong erections.

Sildenafil is the active ingredient and the name for generic Viagra.

Cialis is the brand name for tadalafil (its active ingredient), another PDE5 inhibitor developed by scientists at Eli Lilly around the same time.

Both active ingredients are effective at treating impotence in men of all ages, though there are some nuances to these two popular erectile dysfunction medications.

Phosphodiesterase type-5 (PDE5) inhibitors work by removing the brakes on the erection process. PDE5 is an enzyme that breaks down cGMP, a peptide that helps to relax blood vessel walls and improve blood flow alongside another element called nitric oxide. By inhibiting PDE5, these medications (sildenafil, tadalafil, and vardenafil) let cGMP continue to do its job in the penis: improving blood flow and causing an erection.

These medications are effective in more than 80% of men.

Which Came First, Viagra Or Cialis?

In 1998, Viagra became the first PDE5 inhibitor approved by the U.S. FDA for erectile dysfunction. Cialis was in development at the same time, but it wasn't approved until 2003.

In fact, while these two medications are the best-known and most-popular of the ED medications in the U.S., Cialis was actually third to market.

Levitra® (vardenafil) was approved by the FDA just a few months before Cialis in 2003, making Cialis third to market in a very popular and highly lucrative space.

Until Viagra's approval in 1998, men with erectile dysfunction had no great treatment options and wasn't a common point of discussion (for obvious reasons, guys).

But with a strong promotional effort in the late '90s, Pfizer and then El Lilly helped to make ED – and medicines that can treat the symptoms of ED – mainstream. Viagra famously enlisted spokesmen like soccer legend Pele and former presidential nominee Bob Dole.

Is Viagra Or Cialis More Effective?

When choosing between Cialis and Viagra, effectiveness shouldn't be a concern for most men; these PDE5 inhibitors are mostly the same in terms of effectiveness.

A 2005 paper indicated that Viagra works in about 84% of men and Cialis in about 81% . While there's the chance that some men will react differently to Cialis vs Viagra, and may indeed need to try more than one, your decision should be based mostly on what your doctor recommends.

Both Cialis and Viagra require some sexual stimulation to get things started; just taking the medication and then sitting around waiting isn't likely to work for most men. Both medications also list a maximum use frequency of no more than once daily .

When it comes to Cialis vs Viagra, the big difference between these medications is in the window for sexual intimacy.

Cialis Lasts Longer Than Viagra

As you probably already know, Viagra and Cialis are both taken prior to sexual intimacy. Viagra's FDA-approved prescribing label indicates that it can be taken up to 4 hours before intimacy. It takes 30-60 minutes to start working, but any time in that window men can expect some stimulation to cause an erection.

Cialis has a much longer window for intimacy: up to 36 hours. That's a big deal for a lot of men who don't want to have to plan too far in advance when they take their medication.

Men can take Cialis on a Tuesday morning and still expect to see some effect on Wednesday afternoon, according to its manufacturer.

In addition, Cialis is also available in a lower dose that can be taken once every day in order to prepare you for sexual intimacy at any time. This is called Cialis Daily.

What Are The Available Doses Of Cialis And Viagra?

Viagra and generic sildenafil are available in doses of 25 mg, 50 mg, and 100 mg.

Cialis and generic tadalafil are available in doses of 2.5 mg, 5 mg, 10 mg, and 20 mg. Cialis was first approved at 5,10 and 20 mg for on-demand treatment of erectile dysfunction, but a few years after its initial approval in 2003, Eli Lilly got another approval for a once-daily regimen at 2.5 mg or 5 mg.

Sildenafil is also available in a 20 mg tablet. Why? Because of its effects on blood pressure, Pfizer pursued its testing in Pulmonary Arterial Hypertension (PAH), where it is now approved by the FDA under the brand name Revatio.

This 20mg tablet has been used by some doctors and men for the treatment of ED too, with dosing increments created by combining more than one pill.

In years past, generic sildenafil 20 mg was sometimes cheaper than alternatives at the approved doses for erectile dysfunction of 25, 50, and 100 mg.

Today, Rex MD is proud to offer all sildenafil doses at great prices - you don't need to mix five 20 mg sildenafil tablet to get a 100mg dose.

Which Cialis Dose or Viagra Dose Is Best?

Most men begin treatment with Viagra at 25 mg or 50 mg, allowing them to try its effectiveness and adjust accordingly. Men who don't respond sufficiently to their first sildenafil dose can then get a new prescription for a higher dose, if appropriate.

Most men begin Cialis at 5 mg or 10 mg and can titrate higher if necessary.

Both of these are taken "on demand" in the hours or day before sex.

Some men may find that they'd rather take a pill every day than try to time their sex life. A once-daily low dose of Cialis is a compelling option in this case. Rather than plan ahead and take Cialis in the hours before sex, men can take 2.5 or 5 mg Cialis one every day in order to prime their system for sex any time. The Cialis label indicates this option may be good for men who anticipate sexual intimacy more than a few times a week.

Side Effects Of Cialis And Viagra

PDE5 inhibitors have been around for more than 20 years and taken by millions of men – their side effect profile is well defined after all of these years. But they are prescription medications for a reason: they can have serious side effects and can be dangerous for the wrong people.

Viagra's most common mild side effects include:

• headache
• facial flushing
• upset stomach
• dyspepsia
• nasal congestion
• abnormal vision
• back pain
• dizziness
• rash 

Less common adverse reactions (in <2% of patients during clinical trials) included heart-attack symptoms, sudden vision problems, seizures, prolonged erection, and priapism.

For full details see the Viagra prescribing label.

Cialis' most common mild side effects includeL

• headaches
• dyspepsia
• nasopharyngitis
• back pain
• respiratory infection
• flushing
• limb pain

Less common reactions in <2% of patients included chest pain, sudden decrease in hearing, tinnitus, face edema, blurred vision, and some others. For full details, see the FDA's approved Cialis label .

Importantly, patients considering Viagra or Cialis should not take either of these ED medications if they are already taking nitrates or alpha-blockers; take the medication riociguat; have high blood pressure or low blood pressure; are allergic to sildenafil or tadalafil; or are not healthy enough for sexual activity.

Men with diabetes, heart disease, enlarged prostate or prostate problems like benign prostatic hyperplasia should talk to a doctor before taking an erectile dysfunction drug. Make sure to connect with a doctor about a recommended dose and to find out the best ED medication for you .

The Takeaway: Which Should You Take, Cialis Or Viagra?

Men will find that one or another of these ED medications will work for them, but Cialis (tadalafil) has become a strong contender for most men considering the larger window of opportunity (36 hours).

And, Cialis Daily (low-dose tadalafil) is a popular option for men who want to have sex more often and with less pill-popping hassle.

While earlier research publications have been inconclusive around preference, a study from 2017 looking at a host of tadalafil and sildenafil reviews found that the scales are tipped in favor of tadalafil. Sildenafil and tadalafil have similar efficacy, and the researchers concluded that, "[tadalafil] significantly improves patients’ sexual confidence. Furthermore, patients and their partners prefer tadalafil to sildenafil. Hence, tadalafil may be a better choice for ED treatment."

"[tadalafil] significantly improves patients’ sexual confidence. Furthermore, patients and their partners prefer tadalafil to sildenafil. Hence, tadalafil may be a better choice for ED treatment."

Guys may also find that one of these options doesn't agree with them based on side effects, which a doctor can help you determine after first diagnosis and treatment.

"Tadalafil versus sildenafil really comes down to patient preference," says Dr. Anthony Puopolo, head of Rex MD's affiliated medical team. "I've had patients who've tried both and have a strong preference for one over the other. For guys who like tadalafil, it's usually a matter of timing: tadalafil gives you more time for intimacy, and many men prefer that lack of pressure. For patients who stick with sildenafil, the feedback I hear is that it just works really well. I think for most men who get started with an ED medication, they shouldn't overthink the issue. Effective treatment is the first priority, and their physician can help guide them in the right direction later if necessary."

Sources

Label: VIAGRA (sildenafil citrate) tablets

FULL PRESCRIBING INFORMATION: CONTENTS* 

Direct comparison of tadalafil with sildenafil for the treatment of erectile dysfunction: a systematic review and meta-analysis   

Comparison of clinical trials with sildenafil, vardenafil and tadalafil in erectile dysfunction