Tadalafil, commonly known by its brand name Cialis, is a widely used medication for erectile dysfunction (ED). Often referred to as “the weekend pill,” it allows for greater spontaneity in sexual activity due to its long-lasting effects. If you’re considering or currently using tadalafil, understanding its potential interactions with other medications is crucial for ensuring safe and effective treatment.

What is tadalafil?

Tadalafil belongs to a class of drugs known as phosphodiesterase type 5 (PDE5) inhibitors. These medications work by relaxing blood vessels and enhancing blood flow to your penis, helping you get an erection when sexually stimulated. In addition to treating ED, tadalafil is also prescribed for conditions like benign prostatic hyperplasia (BPH, also known as benign prostate enlargement) and pulmonary arterial hypertension (high blood pressure in the lungs). [1]

What is a drug interaction?

A drug interaction happens when one medication changes how another medication works. This can occur when you take more than one drug at the same time, or when you consume certain foods or drinks. These interactions can make a medication less effective or cause harmful side effects.

Drug interactions with tadalafil

Certain drugs can influence how tadalafil is metabolised in the body, potentially leading to increased adverse effects or reduced effectiveness. Here are some notable drugs that may interact with tadalafil:

Blood pressure medications

Tadalafil can interact with blood pressure drugs, such as nitrates [2] and alpha blockers, leading to a potentially dangerous drop in blood pressure, dizziness or fainting. [3]

Certain antibiotics

Antibiotics such as clarithromycin, erythromycin, and telithromycin are known to interact with tadalafil. They can elevate levels of tadalafil in your bloodstream, raising the risk of side effects such as low blood pressure and dizziness. Another antibiotic, rifampin, can decrease the effectiveness of tadalafil by lowering its levels in the blood, which may prevent it from working as intended. [3]

Other tadalafil interactions

Food interactions

One of the main food interactions with tadalafil involves grapefruit and grapefruit juice. Grapefruit consumption can increase tadalafil concentrations in the bloodstream, leading to an increased risk of side effects such as low blood pressure, dizziness and headaches. [4]

Disease interactions

People with severe heart conditions should not use tadalafil, as sexual activity can put additional strain on the heart. [5] Tadalafil should not be used in those with pulmonary veno-occlusive disease (PVOD), as it may worsen the condition. [6] Those with conditions that predispose them to prolonged erections (for example sickle cell anaemia, multiple myeloma or leukaemia) should avoid tadalafil due to the risk of priapism (a persistent, painful erection). [7]

Tadalafil side effects

Like all medications, PDE5 inhibitors like tadalafil can cause some minor side effects. Some of the most common side effects are:

• Nasal congestion
• Facial flushing
• Stomach pain
• Headaches

Seek immediate medical attention if you experience serious adverse effects including: sudden loss of vision, hearing loss, chest pain or signs of an allergic reaction (rashes, itching, difficulty breathing or swelling of the eyes, lips, tongue or throat).

At MedExpress, our clinicians assess your medical history and medications to find a safe treatment option for you. Find out what treatment is suitable for you on our website.

References

1. NHS. About tadalafil. Available at: https://www.nhs.uk/medicines/tadalafil/about-tadalafil/ (Accessed: 19 December 2024).
2. Kloner RA, Hutter AM, Emmick JT, Mitchell MI, Denne J, Jackson G. Time course of the interaction between tadalafil and nitrates. J Am Coll Cardiol. 2003 Nov 19;42(10):1855-60. doi: 10.1016/j.jacc.2003.09.023. PMID: 14642699.
3. Schwartz BG, Kloner RA. Drug interactions with phosphodiesterase-5 inhibitors used for the treatment of erectile dysfunction or pulmonary hypertension. Circulation. 2010 Jul 6;122(1):88-95. doi: 10.1161/CIRCULATIONAHA.110.944603. PMID: 20606131.
4. Bailey DG, Dresser GK. Interactions between grapefruit juice and cardiovascular drugs. Am J Cardiovasc Drugs. 2004;4(5):281-97. doi: 10.2165/00129784-200404050-00002. PMID: 15449971.
5. NHS. Who can and cannot take tadalafil. Available at: https://www.nhs.uk/medicines/tadalafil/who-can-and-cannot-take-tadalafil/ (Accessed: 19 December 2024)
6. MayoClinic. Tadalafil (oral route). Available at: https://www.mayoclinic.org/drugs-supplements/tadalafil-oral-route/description/drg-20067204 (Accessed: 19 December 2024)
7. Fahmy G, Hess J. Tadalafil [Internet]. PubMed. Treasure Island (FL): StatPearls Publishing; 2024. Available from: https://www.ncbi.nlm.nih.gov/books/NBK603743/