Drug Interaction Report

Medications containing local anesthetics such as procaine penicillin may cause methemoglobinemia, a rare condition that can lead to oxygen deprivation in tissues and vital organs due to reduced oxygen-carrying capacity of the blood. The risk is increased when combined with other medications that can also induce methemoglobinemia such as PHENobarbital. Individuals may be more susceptible to developing methemoglobinemia during treatment with these medications if they are very young (especially neonates and infants) or have diseases of the heart or lungs, certain genetic predispositions, or glucose-6-phosphate dehydrogenase deficiency. Close medical supervision is necessary when medications that can cause methemoglobinemia are used together. Signs and symptoms of methemoglobinemia may occur immediately or hours after treatment. Patients or their caregivers should seek immediate medical attention if they develop gray discoloration of the skin, abnormal blood coloration, nausea, headache, dizziness, lightheadedness, fatigue, shortness of breath, rapid or shallow breathing, a rapid heartbeat, palpitation, anxiety, or confusion. 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.

Ask your doctor before using PHENobarbital together with ethanol (alcohol), this can add to dizziness, drowsiness and other side effects of PHENobarbital. Be careful if you drive or do activities that require you to be awake and alert. Talk with your doctor before using any medications together, or drinking alcohol with PHENobarbital. 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.