STD Home > Other Medications That Can Interact With Ritonavir

Ritonavir may decrease the level of methadone in your blood, perhaps making it less effective or perhaps even causing methadone withdrawal symptoms. Your healthcare provider may need to increase your methadone dosage to prevent this interaction from occurring.
Ritonavir may increase the level of methamphetamine in your blood, possibly increasing the risk of dangerous side effects. Ritonavir should not be combined with street versions (illegal versions) of methamphetamine. If you are taking the prescription version of methamphetamine, your healthcare provider may need to decrease your methamphetamine dosage.
Both ritonavir capsules and oral solution contain alcohol. It is not a good idea to take ritonavir and metronidazole together, as dangerous side effects may occur due to the alcohol in ritonavir.
Other Protease Inhibitors
Ritonavir usually increases the level of other protease inhibitors in the blood. In fact, this is usually used as a beneficial drug interaction in order to make other protease inhibitors more effective.
Phosphodiesterase Type 5 Inhibitors (PDE5 Inhibitors)
Ritonavir can increase the level of PDE5 inhibitors in your blood, increasing your risk of side effects. Your healthcare provider may recommend a lower-than-typical dosage for your PDE5 inhibitor while you are taking ritonavir.
PDE5 inhibitors are used to treat erectile dysfunction or pulmonary arterial hypertension. Specific dosing recommendations are available for combining ritonavir with a PDE5 inhibitor if the PDE5 inhibitor is used to treat erectile dysfunction. Also, specific dosing recommendations are available for combining ritonavir with tadalafil when tadalafil is used to treat pulmonary arterial hypertension.
However, at this time it is not recommended to combine ritonavir with sildenafil when sildenafil is used to treat pulmonary arterial hypertension, as a safe and effective dosing regimen has not yet been determined for this situation.
Pimozide and ritonavir should not be taken together, due to the risk of dangerous reactions.
Written by/reviewed by:
Last reviewed by: Kristi Monson, PharmD;
Last updated/reviewed:
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