Tadalafil Interactions Guide

Kristin Hall, FNP

Medically reviewed by Kristin Hall, FNP

Written by Our Editorial Team

Last updated 2/11/2021

If you’re considering taking the active ingredient in Cialis, also known as tadalafil, there are some things you need to know. 

Tadalafil is an effective treatment for erectile dysfunction, and when compared to other medications in the space like Viagra, it has a longer effective time from dose to dose. 

It can even be taken daily—it was the first drug of its kind approved for daily ED treatment.

Erections and Erectile Dysfunction

There are a few things you should know about what’s up (or isn’t) down there.

Erections are the result of two primary processes: increased bloodflow to the penis’s blood vessels, and the trapping of that blood in the penis in two long champers called the corpora cavernosa. 

When you become aroused, your brain sends chemical signals to your body to dilate the blood vessels in the penis, allowing blood to flow in. The blood becomes trapped in the corpora cavernosa, keeping you erect. 

Erectile dysfunction, as you might suspect, is the condition of something gone awry in those two processes.

There are many factors that can cause erectile dysfunction, but some of the most common include: heart disease, diabetes, high cholesterol, high blood pressure, obesity, depression, anxiety, illicit drug use, excessive alcohol use and performance anxiety to name a few. 

And because of the variety of potential causes, it’s a fairly common condition. The National Institutes of Health say that an estimated 30 million to 50 million men nationwide have some degree of erectile dysfunction. 

They define erectile dysfunction as a “condition in which you are unable to get or keep an erection firm enough for satisfactory sexual intercourse.” 

That means that it’s technically ED when you get an incomplete or partial erection.

Viagra online

Genuine Viagra® makes it possible

What Is Tadalafil?

Tadalafil is one of the proven-effective treatments on the market to get your soldier back in action. 

It’s a phosphodiesterase type 5 (PDE5) inhibitor, which sustains dilation of your blood vessels and the subsequent increase of blood flow to the soft tissue of your penis. 

Tadalafil differs from other PDE5 inhibitors in that it has a significantly larger time frame of efficacy. 

Unlike Viagra, for instance, which can work for a few hours after the medication is taken, Tadalafil can be effective for up to 36 hours from just a single dose, according to the National Library of Medicine.

ED treatments, delivered

Generic for Viagra (sildenafil)

The more affordable FDA-approved medication that treats Erectile Dysfunction at a quarter of the cost. 🙌

Generic for Cialis (tadalafil)

Affordable and helps get the job done. Generic Cialis helps you get and maintain your erections through a simple, daily dosage.


The OG Little Blue Pill that made its name as the first prescription Erectile Dysfunction treatment.


Cialis helps you get and keep stronger erections with a daily or as-needed pill.

Tadalafil Side Effects and Drug Interactions

Like most medications, tadalafil is not without side effects and potential negative drug interactions. 

The most commonly discussed complication that can arise from taking tadalafil is related to blood pressure, particularly when taking tadalafil with alpha blockers

Because PDE5 inhibitors cause dilation of blood vessels, they can also be used to treat certain types of hypertension. That sounds like a benefit, but it’s the major reason why you should talk to your healthcare provider before using tadalafil. particularly if you have a heart condition, or if you use medication for high blood pressure.

The most commonly reported side effects were headache, indigestion, back pain, muscle pain, flushing and stuffy nose. A small number of patients also reported abnormal vision. If you have vision loss you need to stop the medication immediately and seek emergency assistance.

One of the biggest warnings we can give you is not to take tadalafil alongside other medications for ED—particularly other PDE5 inhibitors. As we mentioned earlier, these drugs can cause sudden and severe drops in blood pressure, which can lead to serious consequences including death. 

Using tadalafil alongside other drugs like Viagra might erroneously seem like a good idea, but in reality it could be a life-endingly bad one.

Any heart medications, blood pressure medications, or other drugs with the potential to cause blood pressure interactions should be reported to your healthcare provider before taking tadalafil for the same reasons. 

That includes alpha-blockers and antihypertensive medications. If you take medications called nitrates, you should not take Tadalafil. Likewise, excessive alcohol consumption could cause complications, according to additional FDA data.

Rare side effects have also included sudden hearing loss, renal impairment, and prolonged erection or priapism. According to the FDA, “Priapism, if not treated promptly, can result in irreversible damage to the erectile tissue. 

Patients who have an erection lasting greater than 4 hours, whether painful or not, should seek emergency medical attention."

Sildenafil citrate

Get hard for 95% cheaper than Viagra

How You Take Tadalafil Matters

It’s important to understand that, while Tadalafil can be taken either as an as-needed drug or as a daily medication, you shouldn’t take as-needed prescriptions as a daily regimen. There’s a simple reason for that: dose size.

According to the FDA, daily doses of tadalafil are typically prescribed much smaller than as-needed. As-needed medication will typically be prescribed either as a 10mg or 20mg dosage, whereas a daily dose will be a fraction of that—typically between 2.5mg and 5mg. 

You almost certainly don’t need 20mg daily tadalafil prescription. Daily doses of smaller measures will maintain the drug in your system without multiplying your risk of side effects, but taking 20mg a day would offer no additional benefits—just added risks.

Tadalafil is a proven safe and effective option for treating erectile dysfunction, and it certainly could be the right solution for you. But there are other factors to consider, even beyond the potential side effects and drug interactions. 

One question you should ask yourself is whether your ED might be psychological—whether insecurity, fear of intimacy, or low self esteem might be contributing to the problem. 

Conditions like anxiety and depression can play a role in performance issues, and if you think that might be the case for you, consult a psychiatrist or mental health professional to see if other treatments might be helpful.

Tadalafil might still be a solution, even if part of the problem is in your other head. If you’re ready to look at treatment options, consult your healthcare provider to see if Tadalafil can help.

If you’re just learning about ED, we have resources available to help you determine if either tadalafil (Cialis) or sildenafil (generic for Viagra) are right for you. 

This article is for informational purposes only and does not constitute medical advice. The information contained herein is not a substitute for and should never be relied upon for professional medical advice. Always talk to your doctor about the risks and benefits of any treatment. Learn more about our editorial standards here.