Concurrent Use of Cialis and Levitra is Contraindicated
No, a patient taking daily Cialis (tadalafil) 5 mg should NOT take Levitra (vardenafil) concurrently for erectile dysfunction. Combining two PDE5 inhibitors simultaneously is not recommended due to the risk of additive vasodilatory effects, hypotension, and increased adverse events without proven additional benefit.
Why Combining PDE5 Inhibitors is Problematic
Mechanism and Safety Concerns
- Both tadalafil and vardenafil work through the same mechanism—inhibiting phosphodiesterase type 5 (PDE5), which prevents the breakdown of cyclic GMP, leading to smooth muscle relaxation and vasodilation 1
- Using two PDE5 inhibitors together creates additive vasodilatory effects that can cause dangerous drops in blood pressure, particularly given tadalafil's long half-life (up to 36 hours) 2
- The most common adverse events with PDE5 inhibitors include headache, flushing, dyspepsia, nasal congestion, and dizziness—all of which would be amplified with concurrent use 3
Evidence on Combination Therapy
- While one small study examined combining daily tadalafil 5 mg with sildenafil 50 mg as needed in patients with severe ED, this was a research protocol with specific monitoring, not standard clinical practice 4
- Current guidelines from the European Association of Urology (2025) and American Urological Association (2018) do not support combining different PDE5 inhibitors 3
- The American College of Physicians recommends choosing a single PDE5 inhibitor based on individual patient preferences, including ease of use, cost, and adverse effects profile 3
Recommended Approach
If Current Therapy is Inadequate
- First, verify proper use: Ensure the patient is using tadalafil correctly with adequate sexual stimulation, as incorrect use accounts for many treatment failures 3
- Consider dose optimization: If daily tadalafil 5 mg is insufficient, switching to on-demand higher-dose tadalafil (10-20 mg) or switching to a different single PDE5 inhibitor like vardenafil may be more appropriate 3
- Evaluate for testosterone deficiency: Men with ED and low testosterone respond better to PDE5 inhibitors when combined with testosterone therapy rather than combining two PDE5 inhibitors 3
Alternative Strategies for PDE5 Inhibitor Non-Responders
- Consider switching between PDE5 inhibitors rather than combining them, though evidence for switching is limited 3
- Evaluate for other therapies such as intracavernous injection therapy, vacuum erection devices, or low-intensity shockwave therapy 3
- Assess for underlying conditions that may impair response, including inadequate testosterone levels, severe vascular disease, or psychological factors 3
Critical Safety Point
- Absolute contraindication: Concurrent or intermittent use of nitrates in any form remains an absolute contraindication for all PDE5 inhibitors, including both tadalafil and vardenafil 3, 5
- Patients should be counseled to avoid using multiple PDE5 inhibitors within the same time period due to overlapping pharmacokinetics and increased risk of adverse events 5, 2