Cialis and Grapefruit: Is There an Interaction?

Cialis is one of the most well-known medications for treating erectile dysfunction, right up there with Viagra and Stendra.

Approved for use by the FDA, the active ingredient in Cialis, tadalafil, works to increase blood flow to the penis, which can treat erectile dysfunction and help to improve your sexual satisfaction.

This oral medication has also been used in the treatment of benign prostatic hyperplasia, otherwise known as prostate enlargement.

However, despite the many benefits attributed to Cialis, there is a chance that its effectiveness may be affected by an unlikely source: grapefruit.

In this piece, we’ll be examining the way Cialis works to manage erectile dysfunction, how effective it is at this role, and if grapefruit can truly affect its performance.

How Does Grapefruit Affect Cialis?

Let's put it like this, if you were thinking of washing your dose of Cialis down with a glass of grapefruit juice, maybe swap it for a glass of water or orange juice.

According to a study published in the American Journal of Cardiovascular Drugs, grapefruit juice can cause a drug interaction when taken with certain drugs, and Cialis is one of them. 

To explain, a drug interaction occurs when the effects of a medication are altered when another substance is taken. 

These effects may enhance the benefits or reduce the effectiveness of the drug. In some cases, it may cause toxicity.

In the case of grapefruit and Cialis, this liquid or the fruit itself produces an unwanted effect. 

In its role as a PDE-5 inhibitor, tadalafil acts as a vasodilator to promote the flow of blood to the penis. When combined with grapefruit, this effect can cause a serious increase in blood flow around the body, especially when combined with nitrates.

This is because grapefruit can increase the amount of Cialis in your body. It can achieve this by preventing presystemic metabolism — a process where the concentration of Cialis is reduced before it reaches circulation in the body. 

CYP 3A4 (an enzyme in your intestine) is responsible for this metabolism. When inhibited by grapefruit, there can be higher amounts of Cialis in the body.

But this effect isn't limited to just Cialis. Grapefruit has been known to cause similar effects when taken with antihypertensives, as well as other PDE5 inhibitors like sildenafil (generic Viagra) and vardenafil. 

It has even been known to cause strokes when taken with certain migraine medication.

For the best results, avoid drinking or eating grapefruit around the time you intend to use Cialis.

How Long Does Grapefruit Affect Cialis?

According to the journal, American Family Physician, an 8oz glass of grapefruit juice can stay in your digestive system for up to 72 hours.

That being said, anyone taking Cialis should not eat grapefruit or drink grapefruit juice for 3 days before starting the medication.

If you are taking a daily dose of Cialis (a.k.a. tadalafil 5mg), you may not be able to consume grapefruit at all. Be sure to talk to your healthcare provider about this possible tadalafil interaction.

What Are the Effects of Grapefruit on Cialis?

While grapefruit consumption may seem harmless, you may actually experience heightened side effects of Cialis. 

Because Cialis is sometimes used to control pulmonary arterial hypertension, a type of high blood pressure, side effects may be serious if left untreated. 

Keep your eyes open for headaches, memory issues, muscle pain, changes in vision, fainting, shortness of breath, or irregular heartbeat. If you experience these side effects, seek medical advice immediately.

The Long and Short...

Cialis is high up on the recommendation list when it comes to managing erectile dysfunction.

However, its mechanism of action, which causes an increase in blood flow to the penis may affect other body parts, especially when combined with substances like grapefruit. Care must be taken to avoid the effects of grapefruit juice when taking Cialis.

Learn more about the effects Cialis can have on your body by speaking with a qualified healthcare provider.