Are there any contraindications with Tadalafil (Cialis) and Sildenafil (Viagra)?

From the Guidelines

Tadalafil and sildenafil should not be taken together as this is a significant contraindication. Both medications are phosphodiesterase type 5 (PDE5) inhibitors used to treat erectile dysfunction, and combining them can lead to dangerous drops in blood pressure, potentially causing dizziness, fainting, heart attack, or stroke 1. These medications work through the same mechanism - they increase blood flow to the penis by relaxing blood vessels - and taking them simultaneously creates an additive effect that amplifies side effects.

Key Contraindications

• Concurrent use of nitrates in any form is a contraindication for oral PDE-5 inhibitor therapy, as it can cause severe, potentially fatal drops in blood pressure 1.
• Other contraindications include using alpha-blockers without proper dosing adjustments, uncontrolled high or low blood pressure, recent stroke or heart attack, and certain eye conditions like non-arteritic anterior ischemic optic neuropathy.

Important Considerations

• If you're currently taking one PDE5 inhibitor and considering switching to another, wait at least 24 hours after taking sildenafil or 48-72 hours after tadalafil before starting the new medication.
• Very-low-quality evidence evaluating the association of NAION with the use of PDE-5 inhibitors showed that among 4 million veterans aged 50 years or older, PDE-5 inhibitors were not associated with an increased risk for NAION, but were associated with an increased risk for possible NAION 1.
• Prolonged erection and priapism were reported infrequently during postmarketing surveillance, and trials evaluated for this guideline did not report priapism 1.

From the FDA Drug Label

“See FDA-approved patient labeling (Patient Information)” 17. 1 Nitrates Physicians should discuss with patients the contraindication of tadalafil with regular and/or intermittent use of organic nitrates. CONTRAINDICATIONS Sildenafil citrate is contraindicated in patients with: Concomitant use of organic nitrates in any form, either regularly or intermittently, because of the greater risk of hypotension

The main contraindication for both tadalafil and sildenafil is the concomitant use of organic nitrates.

• Tadalafil and nitrates should not be used together due to the risk of hypotension.
• Sildenafil and nitrates should not be used together due to the risk of hypotension. There is no direct information in the labels about the contraindication of using tadalafil and sildenafil together, but both are contraindicated with nitrates 2 3.

From the Research

Contraindications with Tadalafil and Sildenafil

• Tadalafil and sildenafil are contraindicated in patients receiving organic nitrates due to the synergistic decrease in blood pressure 4, 5.
• The interaction between tadalafil and nitrates lasts for 24-48 hours, while the interaction between sildenafil and nitrates lasts for 4-24 hours 4, 5.
• Caution is necessary when using tadalafil or sildenafil with alpha-blockers, as they can cause severe hypotension and syncope 4, 6.
• Tadalafil and sildenafil are safe to use with most antihypertensive agents, but may cause additive decreases in blood pressure 4, 6.
• The use of tadalafil or sildenafil with CYP3A inhibitors can increase their plasma concentrations and influence their side-effect profile, requiring dose adjustment 6.
• The combination of oral tadalafil and bosentan (endothelin receptor antagonist) reduces tadalafil levels and requires dose adjustment 6.