use caution. Use Caution/Monitor.hydrocortisoneMonitor Closely (1)hydrocortisone will decrease the level or effect of tolterodine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.hyoscyamineMonitor Closely (1)hyoscyamine and tolterodine both decrease cholinergic effects/transmission. Use Caution/Monitor.hyoscyamine sprayMonitor Closely (1)hyoscyamine spray and tolterodine both decrease cholinergic effects/transmission. Use Caution/Monitor.idelalisibSerious - Use Alternative (1)idelalisib will increase the level or effect of tolterodine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Idelalisib is a strong CYP3A inhibitor; avoid coadministration with sensitive CYP3A substratesiloperidoneMonitor Closely (4)tolterodine 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.imatinibMinor (1)imatinib will increase the level or effect of tolterodine by affecting hepatic enzyme CYP2D6 metabolism. Minor/Significance Unknown.imipramineMonitor Closely (1)tolterodine and imipramine both decrease cholinergic effects/transmission. Use Caution/Monitor.indinavirMonitor Closely (1)indinavir will increase the level or effect of tolterodine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.ipratropiumMonitor Closely (1)ipratropium and tolterodine both decrease cholinergic effects/transmission. Use Caution/Monitor. Due to the poor systemic absorption of ipratropium, interaction unlikely at regularly recommended dosages.isoniazidMonitor Closely (1)isoniazid will increase the level or effect of tolterodine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.istradefyllineMonitor Closely (1)istradefylline 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.itraconazoleSerious - Use Alternative (1)itraconazole will increase the level or effect of tolterodine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.ivosidenibSerious - Use Alternative (1)ivosidenib will decrease the level or effect of tolterodine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Avoid coadministration of sensitive CYP3A4 substrates with ivosidenib or replace with alternative therapies. If coadministration is unavoidable, monitor patients for loss of therapeutic effect of these drugs.ketoconazoleSerious - Use Alternative (1)ketoconazole will increase the level or effect of tolterodine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Do not exceed tolterodine dose of 2mg qDay when coadministered with strong CYP3A4 inhibitors. lapatinibMonitor Closely (1)lapatinib will increase the level or effect of tolterodine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.larotrectinibMinor (1)larotrectinib will increase the level or effect of tolterodine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.lenacapavirMonitor Closely (1)lenacapavir 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.levodopaMinor (1)tolterodine, 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. .levoketoconazoleSerious - Use Alternative (1)levoketoconazole will increase the level or effect of tolterodine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Do not exceed tolterodine dose of 2mg qDay when coadministered with strong CYP3A4 inhibitors. lofepramineMonitor Closely (1)tolterodine and lofepramine both decrease cholinergic effects/transmission. Use Caution/Monitor.lonafarnibSerious - Use Alternative (1)lonafarnib will increase the level or effect of tolterodine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Avoid coadministration with sensitive CYP3A substrates. If coadministration unavoidable, monitor for adverse reactions and reduce CYP3A substrate dose in accordance with product labeling.lopinavirSerious - Use Alternative (1)lopinavir will increase the level or effect of tolterodine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.lorcaserinMonitor Closely (1)lorcaserin will increase the level or effect of tolterodine by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.loxapineMonitor Closely (3)tolterodine 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 inhaledMonitor Closely (2)loxapine 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.lumefantrineMonitor Closely (2)lumefantrine will decrease the level or effect of tolterodine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. lumefantrine will increase the level or effect of tolterodine by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.maprotilineMonitor Closely (1)tolterodine and maprotiline both decrease cholinergic effects/transmission. Use Caution/Monitor.maravirocMinor (1)maraviroc will increase the level or effect of tolterodine by affecting hepatic enzyme CYP2D6 metabolism. Minor/Significance Unknown.marijuanaMonitor Closely (1)marijuana will increase the level or effect of tolterodine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.Minor (1)marijuana will increase the level or effect of tolterodine by affecting hepatic enzyme CYP2D6 metabolism. Minor/Significance Unknown.meclizineMonitor Closely (1)meclizine and tolterodine both decrease cholinergic effects/transmission. Use Caution/Monitor.mefloquineSerious - Use Alternative (1)mefloquine increases toxicity of tolterodine by QTc interval. Avoid or Use Alternate Drug. Mefloquine may enhance the QTc prolonging effect of high risk QTc prolonging agents.methscopolamineMonitor Closely (1)methscopolamine and tolterodine both decrease cholinergic effects/transmission. Use Caution/Monitor.methylprednisoloneMonitor Closely (1)methylprednisolone will decrease the level or effect of tolterodine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.metronidazoleMonitor Closely (1)metronidazole will increase the level or effect of tolterodine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.miconazole vaginalMonitor Closely (1)miconazole vaginal will increase the level or effect of tolterodine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.mifepristoneSerious - Use Alternative (1)mifepristone will increase the level or effect of tolterodine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. If coadministration necessary in chronic mifepristone therapy, reduce dose of tolterodine IR to 1 mg twice daily and tolterodine ER to 2 mg once daily; monitor for QT prolongation mirabegronMonitor Closely (1)mirabegron will increase the level or effect of tolterodine by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.mitotaneMonitor Closely (1)mitotane 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.nafcillinMonitor Closely (1)nafcillin will decrease the level or effect of tolterodine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.nefazodoneSerious - Use Alternative (1)nefazodone will increase the level or effect of tolterodine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.nelfinavirMonitor Closely (1)nelfinavir will increase the level or effect of tolterodine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.neostigmineMonitor Closely (1)neostigmine increases and tolterodine decreases cholinergic effects/transmission. Effect of interaction is not clear, use caution. Use Caution/Monitor.nevirapineMonitor Closely (1)nevirapine will decrease the level or effect of tolterodine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.nifedipineMonitor Closely (1)nifedipine will increase the level or effect of tolterodine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.nilotinibMonitor Closely (1)nilotinib will increase the level or effect of tolterodine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.Minor (1)nilotinib will increase the level or effect of tolterodine by affecting hepatic enzyme CYP2D6 metabolism. Minor/Significance Unknown.nortriptylineMonitor Closely (1)tolterodine and nortriptyline both decrease cholinergic effects/transmission. Use Caution/Monitor.olanzapineMonitor Closely (3)tolterodine 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.oliceridineMonitor Closely (1)tolterodine 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.onabotulinumtoxinAMonitor Closely (1)onabotulinumtoxinA and tolterodine both decrease cholinergic effects/transmission. Use Caution/Monitor.orphenadrineMonitor Closely (1)tolterodine and orphenadrine both decrease cholinergic effects/transmission. Use Caution/Monitor.oxcarbazepineMonitor Closely (1)oxcarbazepine will decrease the level or effect of tolterodine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.oxybutyninMonitor Closely (1)oxybutynin and tolterodine both decrease cholinergic effects/transmission. Use Caution/Monitor.oxybutynin topicalMonitor Closely (1)oxybutynin topical and tolterodine both decrease cholinergic effects/transmission. Use Caution/Monitor.oxybutynin transdermalMonitor Closely (1)oxybutynin transdermal and tolterodine both decrease cholinergic effects/transmission. Use Caution/Monitor.paliperidoneMonitor Closely (3)tolterodine 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.pancuroniumMonitor Closely (1)pancuronium and tolterodine both decrease cholinergic effects/transmission. Use Caution/Monitor.panobinostatMonitor Closely (1)panobinostat 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.parecoxibMinor (1)parecoxib will increase the level or effect of tolterodine by affecting hepatic enzyme CYP2D6 metabolism. Minor/Significance Unknown.paroxetineSerious - Use Alternative (1)paroxetine will increase the level or effect of tolterodine by affecting hepatic enzyme CYP2D6 metabolism. Avoid or Use Alternate Drug.peginterferon alfa 2bMonitor Closely (1)peginterferon 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.pentobarbitalMonitor Closely (1)pentobarbital will decrease the level or effect of tolterodine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.perphenazineMonitor Closely (3)tolterodine 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.Minor (1)perphenazine will increase the level or effect of tolterodine by affecting hepatic enzyme CYP2D6 metabolism. Minor/Significance Unknown.phenobarbitalMonitor Closely (1)phenobarbital will decrease the level or effect of tolterodine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.phenytoinMonitor Closely (1)phenytoin will decrease the level or effect of tolterodine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.physostigmineMonitor Closely (1)physostigmine increases and tolterodine decreases cholinergic effects/transmission. Effect of interaction is not clear, use caution. Use Caution/Monitor.pilocarpineMonitor Closely (1)pilocarpine increases and tolterodine decreases cholinergic effects/transmission. Effect of interaction is not clear, use caution. Use Caution/Monitor.pimozideMonitor Closely (3)tolterodine 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.posaconazoleMonitor Closely (1)posaconazole will increase the level or effect of tolterodine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.prabotulinumtoxinAMonitor Closely (1)tolterodine, 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.pralidoximeMonitor Closely (1)pralidoxime and tolterodine both decrease cholinergic effects/transmission. Use Caution/Monitor.pramlintideSerious - Use Alternative (1)pramlintide, tolterodine. Either increases effects of the other by pharmacodynamic synergism. Contraindicated. Synergistic inhibition of GI motility.prednisoneMonitor Closely (1)prednisone will decrease the level or effect of tolterodine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.primidoneMonitor Closely (1)primidone will decrease the level or effect of tolterodine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.prochlorperazineMonitor Closely (3)tolterodine decreases levels of prochlorperazine by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor. tolterodine decreases levels of prochlorperazine by pharmacodynamic antagonism. Use Caution/Monitor. prochlorperazine increases effects of tolterodine by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic effects, possible hypoglycemia.promethazineMonitor Closely (3)tolterodine decreases levels of promethazine by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor. tolterodine decreases levels of promethazine by pharmacodynamic antagonism. Use Caution/Monitor. promethazine increases effects of tolterodine by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic effects, possible hypoglycemia.propafenoneMonitor Closely (1)propafenone will increase the level or effect of tolterodine by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor. Use caution when prescribing propafenone concurrently with tolterodine. Concomitant use of propafenone and tolterodine may cause QT prolongation. propanthelineMonitor Closely (1)propantheline and tolterodine both decrease cholinergic effects/transmission. Use Caution/Monitor.protriptylineMonitor Closely (1)tolterodine and protriptyline both decrease cholinergic effects/transmission. Use Caution/Monitor.pyridostigmineMonitor Closely (1)pyridostigmine increases and tolterodine decreases cholinergic effects/transmission. Effect of interaction is not clear, use caution. Use Caution/Monitor.quetiapineMonitor Closely (3)tolterodine decreases levels of quetiapine by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor. tolterodine decreases levels of quetiapine by pharmacodynamic antagonism. Use Caution/Monitor. quetiapine increases effects of tolterodine