by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.butabarbitalMonitor Closely (1)butabarbital will decrease the level or effect of tolterodine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.butalbitalMonitor Closely (1)butalbital will decrease the level or effect of tolterodine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.carbacholMonitor Closely (1)carbachol increases and tolterodine decreases cholinergic effects/transmission. Effect of interaction is not clear, use caution. Use Caution/Monitor.carbamazepineSerious - Use Alternative (1)carbamazepine will decrease the level or effect of tolterodine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.celecoxibMinor (1)celecoxib will increase the level or effect of tolterodine by affecting hepatic enzyme CYP2D6 metabolism. Minor/Significance Unknown.ceritinibSerious - Use Alternative (1)ceritinib will increase the level or effect of tolterodine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.cevimelineMonitor Closely (1)cevimeline increases and tolterodine decreases cholinergic effects/transmission. Effect of interaction is not clear, use caution. Use Caution/Monitor.chloramphenicolSerious - Use Alternative (1)chloramphenicol will increase the level or effect of tolterodine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.chloroquineMinor (1)chloroquine will increase the level or effect of tolterodine by affecting hepatic enzyme CYP2D6 metabolism. Minor/Significance Unknown.chlorpromazineMonitor Closely (3)tolterodine decreases levels of chlorpromazine by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor. tolterodine decreases levels of chlorpromazine by pharmacodynamic antagonism. Use Caution/Monitor. chlorpromazine increases effects of tolterodine by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic effects, possible hypoglycemia.cimetidineSerious - Use Alternative (1)cimetidine will increase the level or effect of tolterodine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.Minor (1)cimetidine will increase the level or effect of tolterodine by affecting hepatic enzyme CYP2D6 metabolism. Minor/Significance Unknown.cisatracuriumMonitor Closely (1)cisatracurium and tolterodine both decrease cholinergic effects/transmission. Use Caution/Monitor.clarithromycinSerious - Use Alternative (1)clarithromycin will increase the level or effect of tolterodine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.clobazamMonitor Closely (1)clobazam will increase the level or effect of tolterodine by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor. Lower doses of drugs metabolized by CYP2D6 may be required when used concomitantly. clomipramineMonitor Closely (1)tolterodine and clomipramine both decrease cholinergic effects/transmission. Use Caution/Monitor.clozapineMonitor Closely (3)tolterodine decreases levels of clozapine by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor. tolterodine decreases levels of clozapine by pharmacodynamic antagonism. Use Caution/Monitor. clozapine increases effects of tolterodine by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic effects, possible hypoglycemia.cobicistatSerious - Use Alternative (1)cobicistat will increase the level or effect of tolterodine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.conivaptanMonitor Closely (1)conivaptan will increase the level or effect of tolterodine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.cortisoneMonitor Closely (1)cortisone will decrease the level or effect of tolterodine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.crizotinibMonitor Closely (1)crizotinib increases levels of tolterodine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Dose reduction may be needed for coadministered drugs that are predominantly metabolized by CYP3A.crofelemerMonitor Closely (1)crofelemer increases levels of tolterodine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Crofelemer has the potential to inhibit CYP3A4 at concentrations expected in the gut; unlikely to inhibit systemically because minimally absorbed.cyclizineMonitor Closely (1)cyclizine and tolterodine both decrease cholinergic effects/transmission. Use Caution/Monitor.cyclobenzaprineMonitor Closely (1)cyclobenzaprine and tolterodine both decrease cholinergic effects/transmission. Use Caution/Monitor.cyclophosphamideMinor (1)cyclophosphamide will increase the level or effect of tolterodine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.cyclosporineMonitor Closely (1)cyclosporine will increase the level or effect of tolterodine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.dabrafenibMonitor Closely (1)dabrafenib will decrease the level or effect of tolterodine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely.dacomitinibSerious - Use Alternative (1)dacomitinib will increase the level or effect of tolterodine by affecting hepatic enzyme CYP2D6 metabolism. Avoid or Use Alternate Drug. Avoid use with CYP2D6 substrates where minimal increases in concentration of the CYP2D6 substrate may lead to serious or life-threatening toxicities. darifenacinMonitor Closely (2)darifenacin will increase the level or effect of tolterodine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. darifenacin and tolterodine both decrease cholinergic effects/transmission. Use Caution/Monitor.Minor (1)darifenacin will increase the level or effect of tolterodine by affecting hepatic enzyme CYP2D6 metabolism. Minor/Significance Unknown.darunavirMonitor Closely (1)darunavir will increase the level or effect of tolterodine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.dasatinibMonitor Closely (1)dasatinib will increase the level or effect of tolterodine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.deferasiroxMonitor Closely (1)deferasirox will decrease the level or effect of tolterodine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.desipramineMonitor Closely (1)tolterodine and desipramine both decrease cholinergic effects/transmission. Use Caution/Monitor.desvenlafaxineMonitor Closely (1)desvenlafaxine will increase the level or effect of tolterodine by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor. Desvenlafaxine inhibits CYP2D6; with higher desvenlafaxine doses (ie, 400 mg) decrease the CYP2D6 substrate dose by up to 50%; no dosage adjustment needed with desvenlafaxine doses <100 mgdexamethasoneMonitor Closely (1)dexamethasone will decrease the level or effect of tolterodine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.DHEA, herbalMonitor Closely (1)DHEA, herbal will increase the level or effect of tolterodine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.dicyclomineMonitor Closely (1)dicyclomine and tolterodine both decrease cholinergic effects/transmission. Use Caution/Monitor.diltiazemMonitor Closely (1)diltiazem will increase the level or effect of tolterodine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.dimenhydrinateMinor (1)dimenhydrinate increases toxicity of tolterodine by pharmacodynamic synergism. Minor/Significance Unknown. Additive anticholinergic effects.diphenhydramineMonitor Closely (1)diphenhydramine and tolterodine both decrease cholinergic effects/transmission. Use Caution/Monitor.Minor (1)diphenhydramine will increase the level or effect of tolterodine by affecting hepatic enzyme CYP2D6 metabolism. Minor/Significance Unknown.donepezilMonitor Closely (1)donepezil increases and tolterodine decreases cholinergic effects/transmission. Effect of interaction is not clear, use caution. Use Caution/Monitor.Minor (1)donepezil decreases effects of tolterodine by pharmacodynamic antagonism. Minor/Significance Unknown.donepezil transdermalMonitor Closely (1)donepezil transdermal, tolterodine. Either decreases effects of the other by pharmacodynamic antagonism. Use Caution/Monitor.dosulepinMonitor Closely (1)tolterodine and dosulepin both decrease cholinergic effects/transmission. Use Caution/Monitor.doxepinMonitor Closely (1)tolterodine and doxepin both decrease cholinergic effects/transmission. Use Caution/Monitor.dronedaroneMonitor Closely (1)dronedarone will increase the level or effect of tolterodine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.Minor (1)dronedarone will increase the level or effect of tolterodine by affecting hepatic enzyme CYP2D6 metabolism. Minor/Significance Unknown.droperidolMonitor Closely (3)tolterodine decreases levels of droperidol by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor. tolterodine decreases levels of droperidol by pharmacodynamic antagonism. Use Caution/Monitor. droperidol increases effects of tolterodine by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic effects, possible hypoglycemia.duloxetineMinor (1)duloxetine will increase the level or effect of tolterodine by affecting hepatic enzyme CYP2D6 metabolism. Minor/Significance Unknown.duvelisibMonitor Closely (1)duvelisib will increase the level or effect of tolterodine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Coadministration with duvelisib increases AUC of a sensitive CYP3A4 substrate which may increase the risk of toxicities of these drugs. Consider reducing the dose of the sensitive CYP3A4 substrate and monitor for signs of toxicities of the coadministered sensitive CYP3A substrate.echothiophate iodideMonitor Closely (1)echothiophate iodide increases and tolterodine decreases cholinergic effects/transmission. Effect of interaction is not clear, use caution. Use Caution/Monitor.efavirenzMonitor Closely (1)efavirenz will decrease the level or effect of tolterodine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.elagolixMonitor Closely (1)elagolix decreases levels of tolterodine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Elagolix is a weak-to-moderate CYP3A4 inducer. Monitor CYP3A substrates if coadministered. Consider increasing CYP3A substrate dose if needed.eliglustatMonitor Closely (1)eliglustat increases levels of tolterodine by affecting hepatic enzyme CYP2D6 metabolism. Modify Therapy/Monitor Closely. Monitor therapeutic drug concentrations, as indicated, or consider reducing the dosage of the concomitant drug and titrate to clinical effect.elvitegravir/cobicistat/emtricitabine/tenofovir DFMonitor Closely (2)elvitegravir/cobicistat/emtricitabine/tenofovir DF increases levels of tolterodine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Cobicistat is a CYP3A4 inhibitor; contraindicated with CYP3A4 substrates for which elevated plasma concentrations are associated with serious and/or life-threatening events. elvitegravir/cobicistat/emtricitabine/tenofovir DF increases levels of tolterodine by affecting hepatic enzyme CYP2D6 metabolism. Modify Therapy/Monitor Closely. Cobicistat is a CYP2D6 inhibitor; caution with CYP2D6 substrates for which elevated plasma concentrations are associated with serious and/or life-threatening events.encorafenibMonitor Closely (1)encorafenib, tolterodine. affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Encorafenib both inhibits and induces CYP3A4 at clinically relevant plasma concentrations. Coadministration of encorafenib with sensitive CYP3A4 substrates may result in increased toxicity or decreased efficacy of these agents.enzalutamideSerious - Use Alternative (1)enzalutamide will decrease the level or effect of tolterodine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.erythromycin baseSerious - Use Alternative (1)erythromycin base will increase the level or effect of tolterodine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.erythromycin ethylsuccinateSerious - Use Alternative (1)erythromycin ethylsuccinate will increase the level or effect of tolterodine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.erythromycin lactobionateSerious - Use Alternative (1)erythromycin lactobionate will increase the level or effect of tolterodine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.erythromycin stearateSerious - Use Alternative (1)erythromycin stearate will increase the level or effect of tolterodine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.eslicarbazepine acetateMonitor Closely (1)eslicarbazepine acetate will decrease the level or effect of tolterodine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.ethinylestradiolMonitor Closely (1)ethinylestradiol will increase the level or effect of tolterodine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.etravirineMonitor Closely (1)etravirine will decrease the level or effect of tolterodine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.fedratinibMonitor Closely (2)fedratinib will increase the level or effect of tolterodine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Adjust dose of drugs that are CYP3A4 substrates as necessary. fedratinib will increase the level or effect of tolterodine by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor. Adjust dose of drugs that are CYP2D6 substrates as necessary.fesoterodineMonitor Closely (1)fesoterodine and tolterodine both decrease cholinergic effects/transmission. Use Caution/Monitor.fexinidazoleSerious - Use Alternative (1)fexinidazole will increase the level or effect of tolterodine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Fexinidazole inhibits CYP3A4. Coadministration may increase risk for adverse effects of CYP3A4 substrates.flavoxateMonitor Closely (1)flavoxate and tolterodine both decrease cholinergic effects/transmission. Use Caution/Monitor.fluconazoleMonitor Closely (1)fluconazole will increase the level or effect of tolterodine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.fludrocortisoneMonitor Closely (1)fludrocortisone will decrease the level or effect of tolterodine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.fluoxetineSerious - Use Alternative (1)fluoxetine will increase the level or effect of tolterodine by affecting hepatic enzyme CYP2D6 metabolism. Avoid or Use Alternate Drug.fluphenazineMonitor Closely (3)tolterodine decreases levels of fluphenazine by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor. tolterodine decreases levels of fluphenazine by pharmacodynamic antagonism. Use Caution/Monitor. fluphenazine increases effects of tolterodine by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic effects, possible hypoglycemia.fosamprenavirMonitor Closely (1)fosamprenavir will increase the level or effect of tolterodine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.fosaprepitantMonitor Closely (1)fosaprepitant will increase the level or effect of tolterodine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.fosphenytoinMonitor Closely (1)fosphenytoin will decrease the level or effect of tolterodine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.galantamineMonitor Closely (1)galantamine increases and tolterodine decreases cholinergic effects/transmission. Effect of interaction is not clear, use caution. Use Caution/Monitor.Minor (1)galantamine decreases effects of tolterodine by pharmacodynamic antagonism. Minor/Significance Unknown.givosiranSerious - Use Alternative (1)givosiran will increase the level or effect of tolterodine by affecting hepatic enzyme CYP2D6 metabolism. Avoid or Use Alternate Drug. Avoid coadministration of sensitive CYP2D6 substrates with givosiran. If unavoidable, decrease the CYP2D6 substrate dosage in accordance with approved product labeling.glycopyrrolateMonitor Closely (1)glycopyrrolate and tolterodine both decrease cholinergic effects/transmission. Use Caution/Monitor.glycopyrrolate inhaledMonitor Closely (1)glycopyrrolate inhaled and tolterodine both decrease cholinergic effects/transmission. Use Caution/Monitor.glycopyrronium tosylate topicalSerious - Use Alternative (1)glycopyrronium tosylate topical, tolterodine. Either increases effects of the other by pharmacodynamic synergism. Avoid or Use Alternate Drug. Coadministration of glycopyrronium tosylate topical with other anticholinergic medications may result in additive anticholinergic adverse effects.grapefruitMonitor Closely (1)grapefruit will increase the level or effect of tolterodine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.griseofulvinMonitor Closely (1)griseofulvin will decrease the level or effect of tolterodine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.haloperidolMonitor Closely (3)tolterodine decreases levels of haloperidol by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor. tolterodine decreases levels of haloperidol by pharmacodynamic antagonism. Use Caution/Monitor. haloperidol increases effects of tolterodine by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic effects, possible hypoglycemia.Minor (1)haloperidol will increase the level or effect of tolterodine by affecting hepatic enzyme CYP2D6 metabolism. Minor/Significance Unknown.henbaneMonitor Closely (1)henbane and tolterodine both decrease cholinergic effects/transmission. Use Caution/Monitor.homatropineMonitor Closely (1)homatropine and tolterodine both decrease cholinergic effects/transmission. Use Caution/Monitor.huperzine AMonitor Closely (1)huperzine A increases and tolterodine decreases cholinergic effects/transmission. Effect of interaction is not clear,