Ritonavir and Other Protease Inhibitors
Taking both
Viagra and
ritonavir (a protease inhibitor) together can significantly increase the levels of Viagra in the body. Viagra should therefore be used with caution in people taking ritonavir. Viagra has no effects on the levels of ritonavir in the body.
While Viagra has not been studied with other protease inhibitors, a similar reaction is expected.
Amlodipine
Taking both Viagra and
amlodipine together may cause an additional decrease in
blood pressure. If you take amlodipine, consult your healthcare provider prior to taking Viagra.
Alpha Blockers
In previous research studies, when alpha blockers and Viagra 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 from either a sitting position or lying down. Taking a
Viagra dosage above 25 mg within four hours of taking an alpha blocker is not recommended.
Erythromycin
Taking erythromycin and Viagra together may cause your body to metabolize the medicines differently than intended. Your healthcare provider may adjust your dosage to compensate for this.
Saquinavir
Taking
saquinavir and Viagra together may cause your body to metabolize the medicines differently than intended. Your healthcare provider may choose to adjust your dosage.
Antifungals
Taking antifungals and Viagra together may cause your body to metabolize the medicines differently than intended. Your healthcare provider may choose to adjust your dose accordingly.
Nitrates
If you are taking nitrates, you should not use Viagra.
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