Drug Interactions between acetaminophen / dextromethorphan / doxylamine and Nydrazid

Using acetaminophen together with isoniazid may alter the effects of acetaminophen and cause serious side effects that may affect your liver. Call your doctor immediately if you experience a fever, chills, joint pain or swelling, excessive tiredness or weakness, unusual bleeding or bruising, skin rash or itching, loss of appetite, nausea, vomiting, or yellowing of the skin or the whites of your eyes. If your doctor does prescribe these medications together, you may need a dose adjustment or special tests to safely take both medications. It is important to tell your doctor about all other medications you use, including vitamins and herbs. Do not stop using any medications without first talking to your doctor.

Switch to professional interaction data

Consumer information for this interaction is not currently available.

GENERALLY AVOID: Coadministration of isoniazid (INH), with drugs that possess serotonergic activity (e.g., serotonin reuptake inhibitors, 5-HT1 receptor agonists, ergot alkaloids, etc.) may increase the risk of serotonin syndrome, a rare but serious and potentially fatal condition. The proposed mechanism is an increase in serotonin resulting from INH's weak inhibition of monoamine oxidase (the enzyme primarily responsible for breaking down norepinephrine, serotonin, and dopamine) combined with the increase in serotonin from the serotonergic drug(s). In one case report, a patient taking mirtazapine (15 mg nightly) for depression was started on INH (300 mg daily) and pyridoxine (25 mg daily) for tuberculosis prophylaxis following a liver transplant from a donor with latent tuberculosis. Six days following the initiation of INH, the patient developed symptoms consistent with serotonin syndrome (e.g., diarrhea, nausea, tremors, hypertension, and altered mental status) which resolved upon the cessation of INH and mirtazapine. However, consensus on the safety of concomitant use of isoniazid with drugs possessing serotonergic activity is lacking and most of the existing data are limited to case reports.

MANAGEMENT: Until more information is available, coadministration of isoniazid with drugs that possess serotonergic activity (e.g., serotonin reuptake inhibitors, 5-HT1 receptor agonists, ergot alkaloids, etc.) should generally be avoided. If coadministration with a serotonergic drug is required, patients should be advised to promptly seek medical attention if they experience signs and symptoms of serotonin syndrome (including but not limited to confusion, hallucinations, tachycardia, hyperthermia, diaphoresis, shivering, blood pressure lability, neuromuscular abnormalities and/or unexplained gastrointestinal symptoms).

Using dextromethorphan together with doxylamine may increase side effects such as dizziness, drowsiness, confusion, and difficulty concentrating. Some people, especially the elderly, may also experience impairment in thinking, judgment, and motor coordination. You should avoid or limit the use of alcohol while being treated with these medications. Also avoid activities requiring mental alertness such as driving or operating hazardous machinery until you know how the medications affect you. Talk to your doctor if you have any questions or concerns. It is important to tell your doctor about all other medications you use, including vitamins and herbs. Do not stop using any medications without first talking to your doctor.

Switch to professional interaction data