enzyme CYP3A4 metabolism. Use Caution/Monitor.darifenacin and tolterodine both decrease cholinergic effects/transmission. Use Caution/Monitor.darunavirdarunavir will increase the level or effect of tolterodine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.dasatinibdasatinib will increase the level or effect of tolterodine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.deferasiroxdeferasirox will decrease the level or effect of tolterodine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.desipraminetolterodine and desipramine both decrease cholinergic effects/transmission. Use Caution/Monitor.desvenlafaxinedesvenlafaxine 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 mgdexamethasonedexamethasone will decrease the level or effect of tolterodine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.DHEA, herbalDHEA, herbal will increase the level or effect of tolterodine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.dicyclominedicyclomine and tolterodine both decrease cholinergic effects/transmission. Use Caution/Monitor.diltiazemdiltiazem will increase the level or effect of tolterodine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.diphenhydraminediphenhydramine and tolterodine both decrease cholinergic effects/transmission. Use Caution/Monitor.donepezildonepezil increases and tolterodine decreases cholinergic effects/transmission. Effect of interaction is not clear, use caution. Use Caution/Monitor.donepezil transdermaldonepezil transdermal, tolterodine. Either decreases effects of the other by pharmacodynamic antagonism. Use Caution/Monitor.dosulepintolterodine and dosulepin both decrease cholinergic effects/transmission. Use Caution/Monitor.doxepintolterodine and doxepin both decrease cholinergic effects/transmission. Use Caution/Monitor.dronedaronedronedarone will increase the level or effect of tolterodine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.droperidoltolterodine 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.duvelisibduvelisib 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 iodideechothiophate iodide increases and tolterodine decreases cholinergic effects/transmission. Effect of interaction is not clear, use caution. Use Caution/Monitor.efavirenzefavirenz will decrease the level or effect of tolterodine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.elagolixelagolix 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.eliglustateliglustat 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 DFelvitegravir/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.encorafenibencorafenib, 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.eslicarbazepine acetateeslicarbazepine acetate will decrease the level or effect of tolterodine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.ethinylestradiolethinylestradiol will increase the level or effect of tolterodine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.etravirineetravirine will decrease the level or effect of tolterodine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.fedratinibfedratinib 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.fesoterodinefesoterodine and tolterodine both decrease cholinergic effects/transmission. Use Caution/Monitor.flavoxateflavoxate and tolterodine both decrease cholinergic effects/transmission. Use Caution/Monitor.fluconazolefluconazole will increase the level or effect of tolterodine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.fludrocortisonefludrocortisone will decrease the level or effect of tolterodine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.fluphenazinetolterodine 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.fosamprenavirfosamprenavir will increase the level or effect of tolterodine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.fosaprepitantfosaprepitant will increase the level or effect of tolterodine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.fosphenytoinfosphenytoin will decrease the level or effect of tolterodine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.galantaminegalantamine increases and tolterodine decreases cholinergic effects/transmission. Effect of interaction is not clear, use caution. Use Caution/Monitor.glycopyrrolateglycopyrrolate and tolterodine both decrease cholinergic effects/transmission. Use Caution/Monitor.glycopyrrolate inhaledglycopyrrolate inhaled and tolterodine both decrease cholinergic effects/transmission. Use Caution/Monitor.grapefruitgrapefruit will increase the level or effect of tolterodine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.griseofulvingriseofulvin will decrease the level or effect of tolterodine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.haloperidoltolterodine 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.henbanehenbane and tolterodine both decrease cholinergic effects/transmission. Use Caution/Monitor.homatropinehomatropine and tolterodine both decrease cholinergic effects/transmission. Use Caution/Monitor.huperzine Ahuperzine A increases and tolterodine decreases cholinergic effects/transmission. Effect of interaction is not clear, use caution. Use Caution/Monitor.hydrocortisonehydrocortisone will decrease the level or effect of tolterodine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.hyoscyaminehyoscyamine and tolterodine both decrease cholinergic effects/transmission. Use Caution/Monitor.hyoscyamine sprayhyoscyamine spray and tolterodine both decrease cholinergic effects/transmission. Use Caution/Monitor.iloperidonetolterodine decreases levels of iloperidone by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor.tolterodine decreases levels of iloperidone by pharmacodynamic antagonism. Use Caution/Monitor.iloperidone increases effects of tolterodine by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic effects, possible hypoglycemia.iloperidone increases levels of tolterodine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Iloperidone is a time-dependent CYP3A inhibitor and may lead to increased plasma levels of drugs predominantly eliminated by CYP3A4.imipraminetolterodine and imipramine both decrease cholinergic effects/transmission. Use Caution/Monitor.indinavirindinavir will increase the level or effect of tolterodine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.ipratropiumipratropium and tolterodine both decrease cholinergic effects/transmission. Use Caution/Monitor. Due to the poor systemic absorption of ipratropium, interaction unlikely at regularly recommended dosages.isoniazidisoniazid will increase the level or effect of tolterodine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.istradefyllineistradefylline will increase the level or effect of tolterodine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Istradefylline 40 mg/day increased peak levels and AUC of CYP3A4 substrates in clinical trials. This effect was not observed with istradefylline 20 mg/day. Consider dose reduction of sensitive CYP3A4 substrates.lapatiniblapatinib will increase the level or effect of tolterodine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.lenacapavirlenacapavir will increase the level or effect of tolterodine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Lencapavir may increase CYP3A4 substrates initiated within 9 months after last SC dose of lenacapavir, which may increase potential risk of adverse reactions of CYP3A4 substrates.lofepraminetolterodine and lofepramine both decrease cholinergic effects/transmission. Use Caution/Monitor.lorcaserinlorcaserin will increase the level or effect of tolterodine by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.loxapinetolterodine decreases levels of loxapine by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor.tolterodine decreases levels of loxapine by pharmacodynamic antagonism. Use Caution/Monitor.loxapine increases effects of tolterodine by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic effects, possible hypoglycemia.loxapine inhaledloxapine inhaled increases effects of tolterodine by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic effects, possible hypoglycemia.tolterodine decreases levels of loxapine inhaled by pharmacodynamic antagonism. Use Caution/Monitor.lumefantrinelumefantrine will increase the level or effect of tolterodine by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.lumefantrine will decrease the level or effect of tolterodine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.maprotilinetolterodine and maprotiline both decrease cholinergic effects/transmission. Use Caution/Monitor.marijuanamarijuana will increase the level or effect of tolterodine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.meclizinemeclizine and tolterodine both decrease cholinergic effects/transmission. Use Caution/Monitor.methscopolaminemethscopolamine and tolterodine both decrease cholinergic effects/transmission. Use Caution/Monitor.methylprednisolonemethylprednisolone will decrease the level or effect of tolterodine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.metronidazolemetronidazole will increase the level or effect of tolterodine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.miconazole vaginalmiconazole vaginal will increase the level or effect of tolterodine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.mirabegronmirabegron will increase the level or effect of tolterodine by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.mitotanemitotane decreases levels of tolterodine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Mitotane is a strong inducer of cytochrome P-4503A4; monitor when coadministered with CYP3A4 substrates for possible dosage adjustments.nafcillinnafcillin will decrease the level or effect of tolterodine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.nelfinavirnelfinavir will increase the level or effect of tolterodine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.neostigmineneostigmine increases and tolterodine decreases cholinergic effects/transmission. Effect of interaction is not clear, use caution. Use Caution/Monitor.nevirapinenevirapine will decrease the level or effect of tolterodine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.nifedipinenifedipine will increase the level or effect of tolterodine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.nilotinibnilotinib will increase the level or effect of tolterodine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.nortriptylinetolterodine and nortriptyline both decrease cholinergic effects/transmission. Use Caution/Monitor.olanzapinetolterodine decreases levels of olanzapine by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor.tolterodine decreases levels of olanzapine by pharmacodynamic antagonism. Use Caution/Monitor.olanzapine increases effects of tolterodine by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic effects, possible hypoglycemia.oliceridinetolterodine increases toxicity of oliceridine by Other (see comment). Use Caution/Monitor. Comment: Anticholinergic drugs may increase risk of urinary retention and/or severe constipation, which may lead to paralytic ileus. Monitor for signs of urinary retention or reduced gastric motility if oliceridine is coadministered with anticholinergics.onabotulinumtoxinAonabotulinumtoxinA and tolterodine both decrease cholinergic effects/transmission. Use Caution/Monitor.orphenadrinetolterodine and orphenadrine both decrease cholinergic effects/transmission. Use Caution/Monitor.oxcarbazepineoxcarbazepine will decrease the level or effect of tolterodine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.oxybutyninoxybutynin and tolterodine both decrease cholinergic effects/transmission. Use Caution/Monitor.oxybutynin topicaloxybutynin topical and tolterodine both decrease cholinergic effects/transmission. Use Caution/Monitor.oxybutynin transdermaloxybutynin transdermal and tolterodine both decrease cholinergic effects/transmission. Use Caution/Monitor.paliperidonetolterodine decreases levels of paliperidone by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor.tolterodine decreases levels of paliperidone by pharmacodynamic antagonism. Use Caution/Monitor.paliperidone increases effects of tolterodine by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic effects, possible hypoglycemia.pancuroniumpancuronium and tolterodine both decrease cholinergic effects/transmission. Use Caution/Monitor.panobinostatpanobinostat will increase the level or effect of tolterodine by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor. Panobinostat can increase the levels and effects of sensitive CYP2D6 substrates or those with a narrow therapeutic index CYP2D6.peginterferon alfa 2bpeginterferon alfa 2b, tolterodine. Other (see comment). Use Caution/Monitor. Comment: When patients are administered peginterferon alpha-2b with CYP2D6 substrates, the therapeutic effect of these drugs may be altered. Peginterferon alpha-2b may increase or decrease levels of CYP2D6 substrate.pentobarbitalpentobarbital will decrease the level or effect of tolterodine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.perphenazinetolterodine decreases levels of perphenazine by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor.tolterodine decreases levels of perphenazine by pharmacodynamic antagonism. Use Caution/Monitor.perphenazine increases effects of tolterodine by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic effects, possible hypoglycemia.phenobarbitalphenobarbital will decrease the level or effect of tolterodine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.phenytoinphenytoin will decrease the level or effect of tolterodine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.physostigminephysostigmine increases and tolterodine decreases cholinergic effects/transmission. Effect of interaction is not clear, use caution. Use Caution/Monitor.pilocarpinepilocarpine increases and tolterodine decreases cholinergic effects/transmission. Effect of interaction is not clear, use caution. Use Caution/Monitor.pimozidetolterodine decreases levels of pimozide by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor.tolterodine decreases levels of pimozide by pharmacodynamic antagonism. Use Caution/Monitor.pimozide increases effects of tolterodine by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic effects, possible hypoglycemia.posaconazoleposaconazole will increase the level or effect of tolterodine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.prabotulinumtoxinAtolterodine, prabotulinumtoxinA. Either increases effects of the other by pharmacodynamic synergism. Use Caution/Monitor. Use of anticholinergic drugs after administration of botulinum toxin-containing products may potentiate systemic anticholinergic effects.pralidoximepralidoxime and tolterodine both decrease cholinergic