Caution/Monitor.hydrocortisonehydrocortisone will decrease the level or effect of fesoterodine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.hyoscyaminefesoterodine and hyoscyamine both decrease cholinergic effects/transmission. Use Caution/Monitor.hyoscyamine sprayfesoterodine and hyoscyamine spray both decrease cholinergic effects/transmission. Use Caution/Monitor.iloperidonefesoterodine decreases levels of iloperidone by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor.fesoterodine decreases levels of iloperidone by pharmacodynamic antagonism. Use Caution/Monitor.iloperidone increases effects of fesoterodine by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic effects, possible hypoglycemia.imipraminefesoterodine and imipramine both decrease cholinergic effects/transmission. Use Caution/Monitor.indinavirindinavir will increase the level or effect of fesoterodine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.ipratropiumfesoterodine and ipratropium 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 fesoterodine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.lapatiniblapatinib will increase the level or effect of fesoterodine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.lofepraminefesoterodine and lofepramine both decrease cholinergic effects/transmission. Use Caution/Monitor.loxapinefesoterodine decreases levels of loxapine by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor.fesoterodine decreases levels of loxapine by pharmacodynamic antagonism. Use Caution/Monitor.loxapine increases effects of fesoterodine by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic effects, possible hypoglycemia.loxapine inhaledloxapine inhaled increases effects of fesoterodine by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic effects, possible hypoglycemia.fesoterodine decreases levels of loxapine inhaled by pharmacodynamic antagonism. Use Caution/Monitor.lumefantrinelumefantrine will increase the level or effect of fesoterodine by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.lumefantrine will decrease the level or effect of fesoterodine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.maprotilinefesoterodine and maprotiline both decrease cholinergic effects/transmission. Use Caution/Monitor.marijuanamarijuana will increase the level or effect of fesoterodine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.meclizinefesoterodine and meclizine both decrease cholinergic effects/transmission. Use Caution/Monitor.methscopolaminefesoterodine and methscopolamine both decrease cholinergic effects/transmission. Use Caution/Monitor.methylprednisolonemethylprednisolone will decrease the level or effect of fesoterodine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.metronidazolemetronidazole will increase the level or effect of fesoterodine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.miconazole vaginalmiconazole vaginal will increase the level or effect of fesoterodine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.nafcillinnafcillin will decrease the level or effect of fesoterodine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.nefazodonenefazodone will increase the level or effect of fesoterodine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely.nelfinavirnelfinavir will increase the level or effect of fesoterodine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.neostigmineneostigmine increases and fesoterodine decreases cholinergic effects/transmission. Effect of interaction is not clear, use caution. Use Caution/Monitor.nevirapinenevirapine will decrease the level or effect of fesoterodine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.nifedipinenifedipine will increase the level or effect of fesoterodine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.nilotinibnilotinib will increase the level or effect of fesoterodine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.nortriptylinefesoterodine and nortriptyline both decrease cholinergic effects/transmission. Use Caution/Monitor.olanzapinefesoterodine decreases levels of olanzapine by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor.fesoterodine decreases levels of olanzapine by pharmacodynamic antagonism. Use Caution/Monitor.olanzapine increases effects of fesoterodine by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic effects, possible hypoglycemia.oliceridinefesoterodine 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 fesoterodine both decrease cholinergic effects/transmission. Use Caution/Monitor.orphenadrinefesoterodine and orphenadrine both decrease cholinergic effects/transmission. Use Caution/Monitor.oxcarbazepineoxcarbazepine will decrease the level or effect of fesoterodine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.oxybutyninfesoterodine and oxybutynin both decrease cholinergic effects/transmission. Use Caution/Monitor.oxybutynin topicalfesoterodine and oxybutynin topical both decrease cholinergic effects/transmission. Use Caution/Monitor.oxybutynin transdermalfesoterodine and oxybutynin transdermal both decrease cholinergic effects/transmission. Use Caution/Monitor.paliperidonefesoterodine decreases levels of paliperidone by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor.fesoterodine decreases levels of paliperidone by pharmacodynamic antagonism. Use Caution/Monitor.paliperidone increases effects of fesoterodine by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic effects, possible hypoglycemia.pancuroniumfesoterodine and pancuronium both decrease cholinergic effects/transmission. Use Caution/Monitor.pentobarbitalpentobarbital will decrease the level or effect of fesoterodine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.perphenazinefesoterodine decreases levels of perphenazine by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor.fesoterodine decreases levels of perphenazine by pharmacodynamic antagonism. Use Caution/Monitor.perphenazine increases effects of fesoterodine by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic effects, possible hypoglycemia.phenobarbitalphenobarbital will decrease the level or effect of fesoterodine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.phenytoinphenytoin will decrease the level or effect of fesoterodine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.physostigminephysostigmine increases and fesoterodine decreases cholinergic effects/transmission. Effect of interaction is not clear, use caution. Use Caution/Monitor.pilocarpinepilocarpine increases and fesoterodine decreases cholinergic effects/transmission. Effect of interaction is not clear, use caution. Use Caution/Monitor.pimozidefesoterodine decreases levels of pimozide by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor.fesoterodine decreases levels of pimozide by pharmacodynamic antagonism. Use Caution/Monitor.pimozide increases effects of fesoterodine by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic effects, possible hypoglycemia.posaconazoleposaconazole will increase the level or effect of fesoterodine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.prabotulinumtoxinAfesoterodine, 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.pralidoximefesoterodine and pralidoxime both decrease cholinergic effects/transmission. Use Caution/Monitor.prednisoneprednisone will decrease the level or effect of fesoterodine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.primidoneprimidone will decrease the level or effect of fesoterodine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.prochlorperazinefesoterodine decreases levels of prochlorperazine by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor.fesoterodine decreases levels of prochlorperazine by pharmacodynamic antagonism. Use Caution/Monitor.prochlorperazine increases effects of fesoterodine by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic effects, possible hypoglycemia.promethazinefesoterodine decreases levels of promethazine by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor.fesoterodine decreases levels of promethazine by pharmacodynamic antagonism. Use Caution/Monitor.promethazine increases effects of fesoterodine by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic effects, possible hypoglycemia.propanthelinefesoterodine and propantheline both decrease cholinergic effects/transmission. Use Caution/Monitor.protriptylinefesoterodine and protriptyline both decrease cholinergic effects/transmission. Use Caution/Monitor.pyridostigminepyridostigmine increases and fesoterodine decreases cholinergic effects/transmission. Effect of interaction is not clear, use caution. Use Caution/Monitor.quetiapinefesoterodine decreases levels of quetiapine by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor.fesoterodine decreases levels of quetiapine by pharmacodynamic antagonism. Use Caution/Monitor.quetiapine increases effects of fesoterodine by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic effects, possible hypoglycemia.quinidinequinidine will increase the level or effect of fesoterodine by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.quinupristin/dalfopristinquinupristin/dalfopristin will increase the level or effect of fesoterodine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.rapacuroniumfesoterodine and rapacuronium both decrease cholinergic effects/transmission. Use Caution/Monitor.rifapentinerifapentine will decrease the level or effect of fesoterodine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.risperidonefesoterodine decreases levels of risperidone by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor.fesoterodine decreases levels of risperidone by pharmacodynamic antagonism. Use Caution/Monitor.risperidone increases effects of fesoterodine by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic effects, possible hypoglycemia.ritonavirritonavir will increase the level or effect of fesoterodine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.rivastigminefesoterodine decreases effects of rivastigmine by cholinergic effects/transmission. Use Caution/Monitor.rocuroniumfesoterodine and rocuronium both decrease cholinergic effects/transmission. Use Caution/Monitor.rufinamiderufinamide will decrease the level or effect of fesoterodine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.scopolaminefesoterodine and scopolamine both decrease cholinergic effects/transmission. Use Caution/Monitor.secobarbitalsecobarbital will decrease the level or effect of fesoterodine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.solifenacinfesoterodine and solifenacin both decrease cholinergic effects/transmission. Use Caution/Monitor.succinylcholinesuccinylcholine increases and fesoterodine decreases cholinergic effects/transmission. Effect of interaction is not clear, use caution. Use Caution/Monitor.terbinafineterbinafine will increase the level or effect of fesoterodine by affecting hepatic enzyme CYP2D6 metabolism. Modify Therapy/Monitor Closely. Assess need to reduce dose of CYP2D6-metabolized drug.thioridazinefesoterodine decreases levels of thioridazine by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor.fesoterodine decreases levels of thioridazine by pharmacodynamic antagonism. Use Caution/Monitor.thioridazine increases effects of fesoterodine by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic effects, possible hypoglycemia.thiothixenefesoterodine decreases levels of thiothixene by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor.fesoterodine decreases levels of thiothixene by pharmacodynamic antagonism. Use Caution/Monitor.thiothixene increases effects of fesoterodine by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic effects, possible hypoglycemia.tiotropiumfesoterodine and tiotropium both decrease cholinergic effects/transmission. Use Caution/Monitor.tolterodinefesoterodine and tolterodine both decrease cholinergic effects/transmission. Use Caution/Monitor.topiramatetopiramate will decrease the level or effect of fesoterodine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.trifluoperazinefesoterodine decreases levels of trifluoperazine by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor.fesoterodine decreases levels of trifluoperazine by pharmacodynamic antagonism. Use Caution/Monitor.trifluoperazine increases effects of fesoterodine by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic effects, possible hypoglycemia.trihexyphenidylfesoterodine and trihexyphenidyl both decrease cholinergic effects/transmission. Use Caution/Monitor. Potential for additive anticholinergic effects.trimipraminefesoterodine and trimipramine both decrease cholinergic effects/transmission. Use Caution/Monitor.trospium chloridefesoterodine and trospium chloride both decrease cholinergic effects/transmission. Use Caution/Monitor.vecuroniumfesoterodine and vecuronium both decrease cholinergic effects/transmission. Use Caution/Monitor.verapamilverapamil will increase the level or effect of fesoterodine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.voriconazolevoriconazole will increase the level or effect of fesoterodine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.zafirlukastzafirlukast will increase the level or effect of fesoterodine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.ziprasidonefesoterodine decreases levels of ziprasidone by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor.fesoterodine decreases levels of ziprasidone by pharmacodynamic antagonism. Use Caution/Monitor.ziprasidone increases effects of fesoterodine by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic effects, possible hypoglycemia.zotepinefesoterodine decreases levels of zotepine by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor.fesoterodine decreases levels of zotepine by pharmacodynamic antagonism. Use Caution/Monitor.Minor (31)amiodaroneamiodarone will increase the level or effect of fesoterodine by affecting hepatic enzyme CYP2D6 metabolism. Minor/Significance Unknown.asenapineasenapine will increase the level or effect of fesoterodine by affecting hepatic enzyme CYP2D6 metabolism. Minor/Significance Unknown.celecoxibcelecoxib will increase the level or effect of fesoterodine by affecting hepatic enzyme CYP2D6 metabolism. Minor/Significance Unknown.chloroquinechloroquine will increase the level or effect of fesoterodine by affecting hepatic enzyme CYP2D6 metabolism. Minor/Significance Unknown.cimetidinecimetidine will increase the level or effect of fesoterodine by affecting hepatic enzyme CYP2D6 metabolism. Minor/Significance Unknown.darifenacindarifenacin will increase the level or effect of fesoterodine by affecting hepatic enzyme CYP2D6 metabolism. Minor/Significance Unknown.desipraminefesoterodine and desipramine both decrease cholinergic effects/transmission. Minor/Significance Unknown.dimenhydrinatedimenhydrinate increases toxicity of fesoterodine by pharmacodynamic synergism. Minor/Significance Unknown. Additive anticholinergic effects.diphenhydraminediphenhydramine will increase the level or effect of fesoterodine by affecting hepatic enzyme CYP2D6 metabolism. Minor/Significance Unknown.donepezildonepezil decreases effects of fesoterodine by pharmacodynamic antagonism. Minor/Significance Unknown.dronedaronedronedarone will increase the level or effect of fesoterodine by affecting hepatic enzyme CYP2D6 metabolism. Minor/Significance Unknown.eslicarbazepine acetateeslicarbazepine acetate will decrease the level or effect of fesoterodine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.galantaminegalantamine decreases effects of fesoterodine by pharmacodynamic antagonism. Minor/Significance Unknown.haloperidolhaloperidol will increase the level or effect of fesoterodine by affecting hepatic enzyme CYP2D6 metabolism. Minor/Significance Unknown.imatinibimatinib will increase the level or effect of fesoterodine by affecting hepatic enzyme CYP2D6 metabolism. Minor/Significance Unknown.levodopafesoterodine, levodopa. Other (see comment). Minor/Significance Unknown. Comment: Anticholinergic agents may enhance the therapeutic effects of levodopa; however, anticholinergic agents can exacerbate tardive dyskinesia. In high dosage, anticholinergics may decrease the effects of levodopa by delaying its GI absorption. .maravirocmaraviroc will increase the level or effect of fesoterodine by affecting hepatic enzyme CYP2D6 metabolism. Minor/Significance Unknown.marijuanamarijuana will increase the level or effect of fesoterodine by affecting hepatic enzyme CYP2D6 metabolism. Minor/Significance Unknown.nilotinibnilotinib will increase the level or effect of fesoterodine by affecting hepatic enzyme CYP2D6 metabolism. Minor/Significance Unknown.parecoxibparecoxib will increase the level or effect of fesoterodine by affecting hepatic enzyme CYP2D6 metabolism. Minor/Significance Unknown.paroxetineparoxetine will increase the level or effect of fesoterodine by affecting hepatic enzyme CYP2D6 metabolism. Minor/Significance Unknown.perphenazineperphenazine will increase the level or effect of fesoterodine by affecting hepatic enzyme CYP2D6 metabolism. Minor/Significance Unknown.propafenonepropafenone will increase the level or effect of fesoterodine by affecting hepatic enzyme CYP2D6 metabolism. Minor/Significance Unknown.quinacrinequinacrine will increase the level or effect of fesoterodine by affecting hepatic enzyme CYP2D6 metabolism. Minor/Significance Unknown.ranolazineranolazine will increase the level or effect of fesoterodine by affecting hepatic enzyme CYP2D6 metabolism. Minor/Significance Unknown.ritonavirritonavir will increase the level or effect of fesoterodine by affecting hepatic enzyme CYP2D6 metabolism. Minor/Significance Unknown.sertralinesertraline will increase the level or effect of fesoterodine by affecting hepatic enzyme CYP2D6 metabolism. Minor/Significance Unknown.thioridazinethioridazine will increase the level or effect