Amlodipine & Tadalafil Interaction
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Overview
Amlodipine (a dihydropyridine calcium channel blocker) and tadalafil (a PDE5 inhibitor) can produce additive blood pressure lowering when used concurrently. Both drugs are vasodilators, and their combination may cause symptomatic hypotension—particularly with tadalafil used for pulmonary arterial hypertension (PAH) or erectile dysfunction. Clinical vigilance is warranted, especially at initiation.
How does this interaction occur?
Amlodipine blocks L-type calcium channels in vascular smooth muscle, causing vasodilation and reducing peripheral vascular resistance. Tadalafil inhibits phosphodiesterase-5 (PDE5), preventing the breakdown of cyclic GMP, which maintains vasodilation (particularly in corpus cavernosum and pulmonary vasculature). Both drugs lower systemic blood pressure through distinct vascular pathways. The additive vasodilatory effect can cause symptomatic hypotension, dizziness, lightheadedness, and syncope.
Clinical significance
Published pharmacokinetic/pharmacodynamic studies of tadalafil used for PAH documented additive blood pressure lowering with concurrent antihypertensives including calcium channel blockers. The tadalafil prescribing information notes that antihypertensive drugs increase blood pressure lowering effects. In the erectile dysfunction dose range (10–20 mg as needed), blood pressure effects are transient but can still be clinically significant when combined with amlodipine.
Management recommendations
When prescribing tadalafil in patients already on amlodipine, start tadalafil at the lowest effective dose. Counsel patients to rise slowly from sitting or lying positions (orthostatic precautions) to reduce syncope risk. Avoid alcohol, which further lowers blood pressure. Ensure adequate hydration. Reassess blood pressure response after initiating tadalafil.
What to monitor
Blood pressure at initiation and follow-up. Orthostatic blood pressure check (supine then standing after 1 and 3 minutes). Heart rate. Symptoms of hypotension (dizziness, lightheadedness). Sexual function and ED treatment response if applicable.
Alternative options
Alternative PDE5 inhibitors (sildenafil, vardenafil) have similar interaction profiles with calcium channel blockers. If hypotension is problematic, alternative antihypertensives with less vasodilatory effect (e.g., ACE inhibitors, beta-blockers) may be considered for blood pressure management.
Frequently asked questions
References
- [Regulatory] Tadalafil (Cialis) FDA Prescribing Information https://www.accessdata.fda.gov/drugsatfda_docs/label/2018/021368s020lbl.pdf Accessed 2026-03-01.
- [Regulatory] Amlodipine FDA Prescribing Information https://www.accessdata.fda.gov/drugsatfda_docs/label/2011/019787s042lbl.pdf Accessed 2026-03-01.
- [Regulatory] Kloner RA. Pharmacology and drug interaction effects of the phosphodiesterase 5 inhibitors. Am J Cardiol 2006. https://pubmed.ncbi.nlm.nih.gov/16949377/ Accessed 2026-03-01.
Written and fact-checked by PrescriptionDrugs.org Editorial Team
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