or effect of lofexidine by affecting hepatic enzyme CYP2D6 metabolism. Modify Therapy/Monitor Closely. Concomitant use of lofexidine with strong CYP2D6 inhibitors may increase lofexidine plasma levels. Monitor for symptoms of orthostasis and bradycardia if coadministered with a CYP2D6 inhibitor. Consider lofexidine dose reduction.thioridazine and lofexidine both increase QTc interval. Use Caution/Monitor. ECG monitoring is recommended.lonapegsomatropinlonapegsomatropin will decrease the level or effect of thioridazine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Limited published data indicate that growth hormone treatment increases cytochrome P450 (CYP450)-mediated antipyrine clearance. Caution with sensitive CYP substratesloprazolamloprazolam and thioridazine both increase sedation. Use Caution/Monitor.lorazepamlorazepam and thioridazine both increase sedation. Use Caution/Monitor.lorcaserinlorcaserin will increase the level or effect of thioridazine by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.lormetazepamlormetazepam and thioridazine both increase sedation. Use Caution/Monitor.loxapineloxapine and thioridazine both increase antidopaminergic effects, including extrapyramidal symptoms and neuroleptic malignant syndrome. Use Caution/Monitor.loxapine and thioridazine both increase sedation. Use Caution/Monitor.loxapine inhaledloxapine inhaled and thioridazine both increase antidopaminergic effects, including extrapyramidal symptoms and neuroleptic malignant syndrome. Use Caution/Monitor.loxapine inhaled and thioridazine both increase sedation. Use Caution/Monitor.lurasidonelurasidone, thioridazine. Either increases toxicity of the other by Other (see comment). Use Caution/Monitor. Comment: Potential for increased CNS depressant effects when used concurrently; monitor for increased adverse effects and toxicity.maprotilinethioridazine and maprotiline both increase sedation. Use Caution/Monitor.marijuanathioridazine and marijuana both increase sedation. Use Caution/Monitor.meclizinemeclizine decreases levels of thioridazine by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor.meclizine decreases levels of thioridazine by pharmacodynamic antagonism. Use Caution/Monitor.thioridazine increases effects of meclizine by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic effects, possible hypoglycemia.melatoninthioridazine and melatonin both increase sedation. Use Caution/Monitor.meperidinemeperidine and thioridazine both increase sedation. Use Caution/Monitor.meprobamatethioridazine and meprobamate both increase sedation. Use Caution/Monitor.metaproterenolthioridazine increases and metaproterenol decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.metaxalonemetaxalone and thioridazine both increase sedation. Use Caution/Monitor.metforminthioridazine decreases effects of metformin by pharmacodynamic antagonism. Use Caution/Monitor. Patient should be closely observed for loss of blood glucose control; when drugs are withdrawn from a patient receiving metformin, patient should be observed closely for hypoglycemia.methadonethioridazine and methadone both increase QTc interval. Modify Therapy/Monitor Closely.methadone and thioridazine both increase sedation. Use Caution/Monitor.methamphetaminethioridazine will increase the level or effect of methamphetamine by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.thioridazine increases and methamphetamine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.thioridazine, methamphetamine. Mechanism: unknown. Use Caution/Monitor. Risk of cardiac arrhythmia or sudden death, more likely w/thioridazine than other phenothiazines. Interaction more likely in certain predisposed pts. only.methocarbamolmethocarbamol and thioridazine both increase sedation. Use Caution/Monitor.methoxsalenmethoxsalen, thioridazine. Either increases toxicity of the other by pharmacodynamic synergism. Use Caution/Monitor. Additive photosensitizing effects.methscopolaminemethscopolamine decreases levels of thioridazine by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor.methscopolamine decreases levels of thioridazine by pharmacodynamic antagonism. Use Caution/Monitor.thioridazine increases effects of methscopolamine by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic effects, possible hypoglycemia.methylenedioxymethamphetaminethioridazine increases and methylenedioxymethamphetamine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.thioridazine, methylenedioxymethamphetamine. Mechanism: unknown. Use Caution/Monitor. Risk of cardiac arrhythmia or sudden death, more likely w/thioridazine than other phenothiazines. Interaction more likely in certain predisposed pts. only.methylphenidatethioridazine, methylphenidate. Mechanism: unknown. Use Caution/Monitor. Risk of cardiac arrhythmia or sudden death, more likely w/thioridazine than other phenothiazines. Interaction more likely in certain predisposed pts. only.metoclopramidethioridazine and metoclopramide both increase antidopaminergic effects, including extrapyramidal symptoms and neuroleptic malignant syndrome. Use Caution/Monitor.metoprololthioridazine will increase the level or effect of metoprolol by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.mexiletinethioridazine will increase the level or effect of mexiletine by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.midazolammidazolam and thioridazine both increase sedation. Use Caution/Monitor.midazolam intranasalmidazolam intranasal, thioridazine. Either increases toxicity of the other by pharmacodynamic synergism. Modify Therapy/Monitor Closely. Concomitant use of barbiturates, alcohol, or other CNS depressants may increase the risk of hypoventilation, airway obstruction, desaturation, or apnea and may contribute to profound and/or prolonged drug effect.midodrinethioridazine increases and midodrine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.thioridazine, midodrine. Mechanism: unknown. Use Caution/Monitor. Risk of cardiac arrhythmia or sudden death, more likely w/thioridazine than other phenothiazines. Interaction more likely in certain predisposed pts. only.mirabegronmirabegron will increase the level or effect of thioridazine by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.mirtazapinethioridazine and mirtazapine both increase sedation. Use Caution/Monitor.modafinilthioridazine increases and modafinil decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.morphinethioridazine will increase the level or effect of morphine by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.morphine and thioridazine both increase sedation. Use Caution/Monitor.motherwortthioridazine and motherwort both increase sedation. Use Caution/Monitor.moxonidinethioridazine and moxonidine both increase sedation. Use Caution/Monitor.nabilonethioridazine and nabilone both increase sedation. Use Caution/Monitor.nalbuphinenalbuphine and thioridazine both increase sedation. Use Caution/Monitor.nebivololthioridazine will increase the level or effect of nebivolol by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.norepinephrinethioridazine increases and norepinephrine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.thioridazine, norepinephrine. Mechanism: unknown. Use Caution/Monitor. Risk of cardiac arrhythmia or sudden death, more likely w/thioridazine than other phenothiazines. Interaction more likely in certain predisposed pts. only.nortriptylinethioridazine and nortriptyline both increase sedation. Use Caution/Monitor.ofloxacinthioridazine and ofloxacin both increase QTc interval. Modify Therapy/Monitor Closely.olanzapineolanzapine and thioridazine both increase antidopaminergic effects, including extrapyramidal symptoms and neuroleptic malignant syndrome. Use Caution/Monitor.olanzapine and thioridazine both increase sedation. Use Caution/Monitor.oliceridinethioridazine will increase the level or effect of oliceridine by affecting hepatic enzyme CYP2D6 metabolism. Modify Therapy/Monitor Closely. If concomitant use is necessary, may require less frequent oliceridine dosing. Closely monitor for respiratory depression and sedation and titrate subsequent doses accordingly. If inhibitor is discontinued, consider increase oliceridine dosage until stable drug effects are achieved. Monitor for signs of opioid withdrawal. oliceridine, thioridazine. Either increases toxicity of the other by pharmacodynamic synergism. Modify Therapy/Monitor Closely. Profound sedation, respiratory depression, coma, and death may result if coadministered. Reserve concomitant prescribing of these drugs in patients for whom other treatment options are inadequate. Limit dosages and durations to the minimum required. Monitor closely for signs of respiratory depression and sedation. Increased risk of hypotension if ability to maintain blood pressure has been compromised by a reduced blood volume or concurrent administration of certain CNS depressant drugs (eg, phenothiazines or general anesthetics).olodaterol inhaledthioridazine and olodaterol inhaled both increase QTc interval. Use Caution/Monitor. Drugs that prolong the QTc interval and may potentiate the effects of beta2 agonists on the cardiovascular system; increased risk of ventricular arrhythmiasomaveloxoloneomaveloxolone will decrease the level or effect of thioridazine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Omaveloxolone may reduce systemic exposure of sensitive CYP3A4 substrates. Check prescribing information of substrate if dosage modification is needed. onabotulinumtoxinAonabotulinumtoxinA decreases levels of thioridazine by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor.onabotulinumtoxinA decreases levels of thioridazine by pharmacodynamic antagonism. Use Caution/Monitor.thioridazine increases effects of onabotulinumtoxinA by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic effects, possible hypoglycemia.opium tinctureopium tincture and thioridazine both increase sedation. Use Caution/Monitor.orphenadrineorphenadrine and thioridazine both increase sedation. Use Caution/Monitor.osilodrostatosilodrostat and thioridazine both increase QTc interval. Use Caution/Monitor.osimertinibosimertinib and thioridazine both increase QTc interval. Use Caution/Monitor. Conduct periodic monitoring with ECGs and electrolytes in patients taking drugs known to prolong the QTc interval.oxaliplatinoxaliplatin will increase the level or effect of thioridazine by Other (see comment). Use Caution/Monitor. Monitor for ECG changes if therapy is initiated in patients with drugs known to prolong QT interval.oxazepamoxazepam and thioridazine both increase sedation. Use Caution/Monitor.oxybutyninoxybutynin decreases levels of thioridazine by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor.oxybutynin decreases levels of thioridazine by pharmacodynamic antagonism. Use Caution/Monitor.thioridazine increases effects of oxybutynin by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic effects, possible hypoglycemia.oxybutynin topicaloxybutynin topical decreases levels of thioridazine by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor.oxybutynin topical decreases levels of thioridazine by pharmacodynamic antagonism. Use Caution/Monitor.thioridazine increases effects of oxybutynin topical by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic effects, possible hypoglycemia.oxybutynin transdermaloxybutynin transdermal decreases levels of thioridazine by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor.oxybutynin transdermal decreases levels of thioridazine by pharmacodynamic antagonism. Use Caution/Monitor.thioridazine increases effects of oxybutynin transdermal by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic effects, possible hypoglycemia.oxycodonethioridazine will increase the level or effect of oxycodone by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.oxycodone and thioridazine both increase sedation. Use Caution/Monitor.oxymorphonethioridazine will increase the level or effect of oxymorphone by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.oxymorphone and thioridazine both increase sedation. Use Caution/Monitor.ozanimodozanimod and thioridazine both increase QTc interval. Modify Therapy/Monitor Closely. The potential additive effects on heart rate, treatment with ozanimod should generally not be initiated in patients who are concurrently treated with QT prolonging drugs with known arrhythmogenic properties.paliperidonepaliperidone and thioridazine both increase antidopaminergic effects, including extrapyramidal symptoms and neuroleptic malignant syndrome. Use Caution/Monitor.thioridazine and paliperidone both increase QTc interval. Modify Therapy/Monitor Closely.paliperidone and thioridazine both increase sedation. Use Caution/Monitor.pancuroniumpancuronium decreases levels of thioridazine by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor.pancuronium decreases levels of thioridazine by pharmacodynamic antagonism. Use Caution/Monitor.thioridazine increases effects of pancuronium by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic effects, possible hypoglycemia.panobinostatpanobinostat will increase the level or effect of thioridazine 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.papaveretumpapaveretum and thioridazine both increase sedation. Use Caution/Monitor.papaverinethioridazine and papaverine both increase sedation. Use Caution/Monitor.pazopanibthioridazine and pazopanib both increase QTc interval. Use Caution/Monitor.peginterferon alfa 2bpeginterferon alfa 2b, thioridazine. 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.pentazocinepentazocine and thioridazine both increase sedation. Use Caution/Monitor.pentobarbitalpentobarbital and thioridazine both increase sedation. Use Caution/Monitor.perphenazineperphenazine and thioridazine both increase antidopaminergic effects, including extrapyramidal symptoms and neuroleptic malignant syndrome. Use Caution/Monitor.perphenazine and thioridazine both increase sedation. Use Caution/Monitor.phendimetrazinethioridazine increases and phendimetrazine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.thioridazine, phendimetrazine. Mechanism: unknown. Use Caution/Monitor. Risk of cardiac arrhythmia or sudden death, more likely w/thioridazine than other phenothiazines. Interaction more likely in certain predisposed pts. only.phenobarbitalphenobarbital and thioridazine both increase sedation. Use Caution/Monitor.phenterminethioridazine increases and phentermine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.thioridazine, phentermine. Mechanism: unknown. Use Caution/Monitor. Risk of cardiac arrhythmia or sudden death, more likely w/thioridazine than other phenothiazines. Interaction more likely in certain predisposed pts. only.phenylephrinethioridazine increases and phenylephrine decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.thioridazine, phenylephrine. Mechanism: unknown. Use Caution/Monitor. Risk of cardiac arrhythmia or sudden death, more likely w/thioridazine than other phenothiazines. Interaction more likely in certain predisposed pts. only.phenylephrine POthioridazine increases and phenylephrine PO decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor. .thioridazine, phenylephrine PO. Mechanism: unknown. Use Caution/Monitor. Risk of cardiac arrhythmia or sudden death, more likely w/thioridazine than other phenothiazines. Interaction more likely in certain predisposed pts. only.pholcodinethioridazine and pholcodine both increase sedation. Use Caution/Monitor.pimozidepimozide and thioridazine both increase antidopaminergic effects, including extrapyramidal symptoms and neuroleptic malignant syndrome. Use Caution/Monitor.pimozide and thioridazine both increase sedation. Use Caution/Monitor.pirbuterolthioridazine increases and pirbuterol decreases sedation. Effect of interaction is not clear, use caution. Use Caution/Monitor.pitolisantthioridazine will increase the level or effect of pitolisant by affecting hepatic enzyme CYP2D6 metabolism. Modify Therapy/Monitor Closely. If coadministered with strong CYP2D6 inhibitors, initiate pitolisant at 8.9 mg/day and increase after 7 days to maximum of 17.8 mg/day. For patients currently taking pitolisant, reduce pitolisant dose by half upon initiating strong CYP2D6 inhibitors.porfimerthioridazine, porfimer. Mechanism: pharmacodynamic synergism. Use Caution/Monitor. Enhanced photosensitivity.posaconazolethioridazine and posaconazole both increase QTc interval. Modify Therapy/Monitor Closely.pralidoximepralidoxime decreases levels of thioridazine by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor.pralidoxime decreases levels of thioridazine by pharmacodynamic antagonism. Use Caution/Monitor.thioridazine increases effects of pralidoxime by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic effects, possible hypoglycemia.primidoneprimidone and thioridazine both increase sedation. Use Caution/Monitor.procarbazineprocarbazine, thioridazine. Mechanism: pharmacodynamic synergism. Use Caution/Monitor. Excessive sedation.prochlorperazineprochlorperazine and thioridazine both increase antidopaminergic effects, including extrapyramidal symptoms and neuroleptic malignant syndrome. Use Caution/Monitor.prochlorperazine and thioridazine both increase sedation. Use Caution/Monitor.promethazinepromethazine and thioridazine both increase antidopaminergic effects, including extrapyramidal symptoms and neuroleptic malignant syndrome. Use Caution/Monitor.promethazine and thioridazine both increase sedation. Use Caution/Monitor.propanthelinepropantheline decreases levels of thioridazine by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor.propantheline decreases levels of thioridazine