Common adverse effects of Haldol usually include sleepiness, dizziness, rapid heart beat, constipation, excess saliva production and weight gain. Another important adverse effect that occurs commonly is orthostatic hypotension (a lowering of your blood pressure when you are sitting up or standing up). Occasionally this can lead to fainting and falling down, therefore, people taking Haldol should be careful when they change positions. These adverse effects are usually mild and usually go away after the first several days of starting treatment or increasing a dose.
CNS depression potentiated with alcohol, other CNS depressants. Possible neurotoxicity with lithium: monitor, discontinue if occurs. Caution with drugs that prolong the QT interval (eg, ketoconazole, paroxetine). May be potentiated by CYP3A4 or CYP2D6 inhibitors/substrates (eg, itraconazole, nefazodone, buspirone, venlafaxine, alprazolam, fluvoxamine, quinidine, fluoxetine, sertraline, chlorpromazine, promethazine. May be antagonized by CYP3A4 inducers (eg, rifampin, carbamazepine); monitor and adjust doses. May increase intraocular pressure with anticholinergics, antiparkinson agents. Monitor anticoagulants.