From the Guidelines
Taking sildenafil and tadalafil together is not recommended due to potential safety concerns, including increased risk of adverse events and hypotension. The use of PDE-5 inhibitors, such as sildenafil and tadalafil, has been associated with adverse events, including headache, flushing, rhinitis, and dyspepsia, as well as less common effects like visual disturbances and chest pain 1. While high-quality evidence has shown that the incidence of serious adverse events is less than 2%, with no difference between PDE-5 inhibitors and placebo, the combination of these medications may amplify their effects, potentially causing excessive vasodilation and dangerous drops in blood pressure.
Some key points to consider when evaluating the safety of combining sildenafil and tadalafil include:
- The most common adverse effects of PDE-5 inhibitors are headache, flushing, rhinitis, and dyspepsia, with less common effects including visual disturbances, myalgia, nausea, diarrhea, vomiting, dizziness, and chest pain 1.
- Sildenafil was associated with fewer adverse events than non–PDE-5 inhibitors and PDE-5 inhibitors combined with non–PDE-5 inhibitors 1.
- Very-low-quality evidence showed that adverse events did not statistically significantly differ among men receiving sildenafil, tadalafil, and vardenafil, but the combination of these medications may still pose a risk due to their similar mechanisms of action 1.
- PDE-5 inhibitors were not associated with an increased risk for nonarteritic anterior ischemic optic neuropathy (NAION), but were associated with an increased risk for possible NAION, highlighting the need for caution when using these medications, especially in combination 1.
Given the potential risks and lack of strong evidence supporting the safety of combining sildenafil and tadalafil, it is recommended to consult with a healthcare provider before using these medications together, and to consider alternative treatment options, such as adjusting the dosage or switching to a different PDE5 inhibitor.
From the FDA Drug Label
- 11 Combination With Other PDE5 Inhibitors or Erectile Dysfunction Therapies
The safety and efficacy of combinations of tadalafil and other PDE5 inhibitors or treatments for erectile dysfunction have not been studied. Inform patients not to take tadalafil with other PDE5 inhibitors, including ADCIRCA.
Do not take sildenafil tablets, 20 mg with sildenafil citrate tablets, 25 mg, 50 mg and 100 mg or other PDE-5 inhibitors.
The combination of sildenafil and tadalafil is not recommended, as the safety and efficacy of this combination have not been studied. Patients should be informed not to take tadalafil with other PDE5 inhibitors, including sildenafil. Therefore, taking sildenafil and tadalafil together is not safe 2 3.
From the Research
Safety of Sildenafil and Tadalafil
- The overall safety of PDE5 inhibitors, including sildenafil and tadalafil, is good, even in patients with a history of cardiovascular disease 4.
- However, there is a risk of hypotension if nitrates are given concurrently with PDE5 inhibitors 4, 5.
- Common side-effects of PDE5 inhibitors include headache, facial flushing, nasal congestion, and dyspepsia 4.
- Priapism and prolonged erection are rare adverse events associated with PDE5 inhibitors 4.
Interactions between Sildenafil and Tadalafil
- PDE5 inhibitors, including sildenafil and tadalafil, exhibit higher plasma concentrations when co-administered with cytochrome P (CYP) 3A inhibitors, which influences their side-effect profile 6.
- Co-administration of PDE5 inhibitors with nitrates or α-blockers can cause severe hypotension and syncope 6.
- Dose adjustment is necessary when PDE5 inhibitors are co-administered with CYP3A inducers or inhibitors 6.
Comparison of Sildenafil and Tadalafil
- Tadalafil and sildenafil have similar efficacies and overall adverse event rates in the treatment of erectile dysfunction 7.
- Tadalafil significantly improves psychological outcomes compared to sildenafil 7.
- Patients and their partners prefer tadalafil over sildenafil, with no significant difference in adherence and persistence rates between the two medications 7.