Switching Between Tadalafil and Vardenafil: Safety Considerations
Direct Answer
No, this switching pattern is not safe and should be avoided. After taking tadalafil 5 mg for BPH, you must wait at least 48 hours before taking vardenafil, and you cannot safely return to tadalafil just 6 hours after vardenafil 1.
Critical Safety Issue: Overlapping PDE5 Inhibitors
Why This Matters for Cardiac Safety
The primary concern is not about combining two PDE5 inhibitors per se, but rather the absolute contraindication with nitrate medications that could be needed in a cardiac emergency:
Tadalafil requires a 48-hour nitrate-free window - If you develop chest pain or acute coronary syndrome while tadalafil is in your system, emergency providers cannot safely administer life-saving nitroglycerin for at least 48 hours after your last tadalafil dose 1, 2, 3
Vardenafil requires a 24-hour nitrate-free window - Similarly, nitrates cannot be given within 24 hours of vardenafil use 1
The mechanism is life-threatening - Both drugs inhibit phosphodiesterase-5, which when combined with nitrates causes markedly exaggerated vasodilation leading to profound hypotension, myocardial infarction, stroke, or death 2, 3
The Pharmacokinetic Problem
Your proposed timing creates dangerous overlap:
- Tadalafil has a 17.5-hour half-life, meaning it remains active in your body for more than 2 days 2
- Taking vardenafil at 18 hours means tadalafil is still significantly active in your system 4, 5
- Returning to tadalafil after only 6 hours means vardenafil (half-life 4-6 hours) is still active 6
- This creates continuous PDE5 inhibition without any safe window for emergency nitrate administration
Safe Approach to PDE5 Inhibitor Use
If Taking Tadalafil Daily for BPH
You should not switch to vardenafil for erectile dysfunction while on daily tadalafil therapy 1, 4, 5:
- Daily tadalafil 5 mg provides continuous therapeutic levels for BPH symptoms 4, 5
- This same daily dose also improves erectile function in men with both BPH and ED 4, 5
- There is no medical need to add vardenafil when tadalafil addresses both conditions
If You Must Use Different PDE5 Inhibitors
The only safe approach requires complete drug clearance:
- Stop tadalafil and wait 48 hours minimum before taking any other PDE5 inhibitor 1, 2
- After vardenafil, wait 24 hours minimum before resuming tadalafil 1
- This ensures at least one drug is fully cleared before introducing another
Clinical Recommendations
For BPH Management
- Continue tadalafil 5 mg daily as prescribed - This dose effectively treats BPH symptoms and maintains improvement over long-term use 4, 5
- If erectile function is also a concern, the same daily 5 mg dose addresses both conditions simultaneously 4, 5
For Erectile Dysfunction Needs
If you feel vardenafil works better for ED:
- Discuss with your prescriber about switching completely from daily tadalafil to on-demand vardenafil 1
- This would require stopping tadalafil, waiting 48 hours, then using vardenafil as needed 1
- However, you would lose the BPH benefits of daily tadalafil 4, 5
Alternative BPH Treatments
If you prefer on-demand vardenafil for ED, consider alternative BPH medications 1:
- Alpha-blockers (tamsulosin, alfuzosin)
- 5-alpha reductase inhibitors (finasteride, dutasteride)
- These do not interact with PDE5 inhibitors
Critical Safety Warning
Never combine or rapidly switch PDE5 inhibitors without proper clearance time - The risk is not immediate toxicity from the drugs themselves, but rather the inability to safely treat a cardiac emergency with nitrates should one occur 1, 2, 3. Emergency medical personnel must know your complete PDE5 inhibitor history to avoid potentially fatal drug interactions.