In previous research studies, when alpha blockers and Cialis were used at the same time for people with benign prostatic hyperplasia (BPH) or high blood pressure, blood pressure decreased. Also, some people experienced lightheadedness, dizziness, or fainting when standing up from either a sitting or lying position. Your healthcare provider may recommend a lower dosage of Cialis if you are taking an alpha blocker.

 

Taking both Cialis and certain high blood pressure medicines may cause an additional decrease in blood pressure. Consult your healthcare provider prior to taking Cialis with any high blood pressure medicine.

 

Taking both antifungals and Cialis together may cause your body to metabolize the medicines differently than intended. This can result in increased levels of Cialis in the blood. People taking these medicines together should be prescribed a maximum Cialis dosage of 10 mg, and should not take more than one Cialis tablet every 72 hours.

 

Taking both erythromycin and Cialis together may cause your body to metabolize the medicines differently than intended. Your healthcare provider may choose to make necessary dosing adjustments.

 

Drinking grapefruit juice while taking Cialis may cause your body to metabolize the Cialis differently than intended. Your healthcare provider may choose to adjust your dosage.

 

If you are taking nitrates, you should not use Cialis. This includes using recreational drugs called "poppers," which can contain amyl nitrate or butyl nitrate.

 

Taking both Cialis and ritonavir or indinavir (which are HIV protease inhibitors) may cause your body to metabolize the medications differently than intended. People taking these medicines with Cialis are more likely to experience a decrease in blood pressure, fainting, or prolonged erection. If you are taking these medicines together, it is recommended that you take Cialis no more often than every 72 hours, with a maximum dose of Cialis 10 mg. Additionally, other HIV protease inhibitors that have not been studied with Cialis may cause a similar reaction.