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Does CBD Interact With Tadalafil (Cialis)?

CBD may interfere with the body’s ability to metabolize tadalafil (Cialis) — however, the level of risk for this interaction is considered low.

Proceed with caution.

Article By
Daily CBD , last updated on January 31, 2022

Tadalafil (Cialis) is a prescription medication used to treat erectile dysfunction (ED), benign prostatic hyperplasia, and pulmonary arterial hypertension.

ED medications are notorious for interacting with other medications, and there’s a long list of contraindications that come on the package. 

Is it safe to take with CBD? What are the risks of using cannabinoids and ED medications like Cialis? 

Illustration of tadalafil tablets

Does CBD Interact With Tadalafil (Cialis)?

Yes. CBD may interact with tadalafil (Cialis), but the side effects are usually mild. 

CBD and Cialis are both vasodilators, so this combination could lead to a drop in blood pressure, causing dizziness, fatigue, and headaches. 

CBD may increase the risk of a rare but severe side effect called priapism — which is characterized by a painful erection lasting more than 6 hours. This side effect requires immediate medical attention but is extremely rare. 

Always speak to your doctor to get a full picture of your individual level of risk and for advice on safe dosage schedules. 

There are two main ways by which CBD can interact with tadalafil: 

1. Slowed Elimination (Metabolic Inhibition)

When two drugs use up the same enzymes for metabolism in the body, they may compete against each other; this is called metabolic inhibition. This process slows down the metabolism of one or both drugs. After using these drugs regularly, they accumulate more in the body and could cause some unsavory effects.

CBD may inhibit tadalafil’s metabolism in the body. 

The CYP3A4 enzyme extensively metabolizes tadalafil, which also metabolizes CBD. If you take these two drugs together, the plasma levels of tadalafil can increase in the body and stay that way for a longer time. Over a long duration of using both these drugs, there will be a slowdown in the clearance of tadalafil, causing it to last longer and cause more side effects. 

2. Increased Effect (Agonistic Interaction)

When one substance acts like another one, causing the same effects and stimulating their action, they’re called agonists, and their interaction is said to be agonistic. In this case, CBD is an agonist to tadalafil. 

CBD can increase the amount of tadalafil in the body, raising its potency levels and making it long-lasting. However, this also means it can increase the side effects of tadalafil in the body over time. 

It’s always best to talk to your doctor before using CBD with medications.

Similar Medications: CBD & Erectile Dysfunction Medications

Tadalafil (Cialis) is classified as a phosphodiesterase inhibitor. CBD and PDE5 inhibitors all share similar risks for interaction and side effects — the most common being headaches and dizziness. 

Here’s a list of similar medications that share a similar level of risk when combined with CBD:

CBD oil container with a hemp leaf, side to side, over white background

Is It Safe to Take CBD and Tadalafil (Cialis) Together?

The interaction between tadalafil (Cialis) and CBD is considered low risk. CBD could potentiate some of the more serious side effects of Cialis, such as priapism, but this effect is very rare. 

If you experience any pain in your erection or have an erection lasting longer than 6 hours, seek medical attention immediately. 

You should always ask your doctor about health supplements (including CBD) if you’ve been given a prescription for tadalafil or any other prescription medication. 

Is CBD a Viable Alternative to Tadalafil (Cialis)?

CBD (cannabidiol) is not considered a viable alternative to tadalafil (Cialis) in treating erectile dysfunction. 

The effects of CBD on erectile dysfunction and libido are controversial. While some studies show that it enhances them, others have shown that it can negatively affect the male reproductive system.

One study conducted on male mice showed that the chronic use of CBD caused impaired sexual behavior [1]. The more CBD was used, the lower the sexual drive was in these mice. 

A study from 2019 showed that ED was twice as high in men who use cannabis, CBD’s base plant, compared to those that didn’t [2]. 

Another study showed that CBD might reduce symptoms of ED and increase libido by decreasing anxiety in the users [3]. Some people may have anxiety about their sexual performance, leading to a decrease in their libido — relieving anxiety may increase sexual drive. 

The research regarding CBD’s potential as an effective drug to treat erectile dysfunction is still lacking. 

What is Tadalafil (Cialis)? 

Tadalafil is a phosphodiesterase type 5 (PDE5) inhibitor and one of the most commonly used. It is used in the treatment of erectile dysfunction (ED), benign prostatic hyperplasia (BPH), pulmonary arterial hypertension (PAH). 

It was approved for use by the FDA in 2003. In most countries, tadalafil is sold as a prescription-only drug.   

Tadalafil (Cialis) Specs

Drug Name  Tadalafil
Trade Names Cialis, Tazzle, Edsave, Tadacip, Tadalis, Tadil, TD 36, Td-Pill, Zydalis, Amore 36, Erectalis, Forzest, Manforce More, Megalis, Pulmopres, Tadalift
Classification  Phosphodiesterase 5 inhibitor
CYP Metabolism  CYP3A4
Interaction With CBD Metabolic inhibitor, Agonistic
Risk of Interaction  Mild

What Does Tadalafil (Cialis) Do?

Tadalafil works by inhibiting an enzyme called phosphodiesterase 5 (PDE5) in the body. This enzyme is found in corpora cavernosa, vascular smooth muscles, visceral smooth muscles, and platelets. 

Tadalafil increases the blood flow to a flaccid penis, making it erect. It has a longer duration of action than most other phosphodiesterase inhibitors. It can last for up to 36 hours, earning it the name “the weekend pill.” 

Erection is controlled by the release of nitric oxide (NO) from nerve terminals and endothelial cells, leading to a release of cyclic guanosine monophosphate (cGMP) from smooth muscle cells. This release of cGMP causes the muscles of the corpora cavernosa to relax and the vessels to get dilated, allowing blood to flow more easily into the erectile tissue of the penis.

Men that have poor blood flow to the penis or poor nitric oxide production will experience difficulty achieving and maintaining an erection. 

PDE5 prevents blood vessels in the penis from relaxing. It also degrades the cGMP. Besides this, many ED patients have some kind of physical obstructions in their penis, making them unable to get erect. 

Tadalafil inhibits PDE5, increases cGMP level in the corpus cavernosum,  allows more blood to flow into the penis, and causes the penis to get erect long enough to have sex. 

There is a catch, however. Tadalafil needs proper sexual stimulation to do its work. It cannot work if the user is not sexually stimulated.

PDE5 is also present in the pulmonary vasculature. Tadalafil can increase cGMP within pulmonary vascular smooth muscle cells and cause them to relax. In patients with pulmonary arterial hypertension, this can lead to vasodilation of the pulmonary vascular bed and systemic circulation. 

Side Effects of Tadalafil (Cialis)

Tadalafil must be avoided in users with severe heart disease, hypersensitivity to sildenafil, priapism, severe renal and liver disease, stomach ulcers, retinitis pigmentosa, and blood disorders. 

This drug may cause dangerous interactions when combined with some medications, including:

  • Nitrates
  • Antihypertensive medications
  • Guanylate cyclase stimulators
  • CYP3A4 inhibitors
  • CYP3A4 inducers

Tadalafil should not be used with these medications. You should not drink any kind of alcohol while on tadalafil; it could worsen its effects. 

Side Effects of Tadalafil (Cialis)

  • Abdominal pain
  • Abnormal vision
  • Back pain
  • Diarrhea
  • Dyspepsia
  • Headaches
  • Hot flushes
  • Loss of vision
  • Muscle pain
  • Nasal blockage
  • Nausea
  • Prolonged and painful erection
  • Sensitivity to light
  • Skin rash
  • Tingling sensation in the limbs and extremities

Key Takeaways: Is it Safe to Take Tadalafil (Cialis) With CBD?

CBD can slow down tadalafil’s metabolism, making it last longer, but causing more side effects over a long time.

A low dose of both drugs may minimize side effects, but it’s impossible to know how the interaction will affect you. Always talk to your prescribing physician before taking these two drugs together.


  1. Carvalho, R. K., Andersen, M. L., & Mazaro‐Costa, R. (2020). The effects of cannabidiol on male reproductive system: A literature review. Journal of Applied Toxicology, 40(1), 132-150. 
  2. Pizzol, D., Demurtas, J., Stubbs, B., Soysal, P., Mason, C., Isik, A. T., … & Veronese, N. (2019). Relationship between cannabis use and erectile dysfunction: a systematic review and meta-analysis. American journal of men’s health, 13(6), 1557988319892464. 
  3. Blessing, E. M., Steenkamp, M. M., Manzanares, J., & Marmar, C. R. (2015). Cannabidiol as a potential treatment for anxiety disorders. Neurotherapeutics, 12(4), 825-836. 

Learn More About CBD-Drug Interactions

Learn More About CBD-Drug Interactions

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