Drug Interaction Report

Consumer information for this interaction is not currently available.

MONITOR: Tetracyclines may enhance the hypoglycemic effects of insulin and insulin secretagogues (e.g., sulfonylureas, meglitinides). The exact mechanism is unknown; however, proposed mechanisms include increasing the sensitivity of insulin, increasing the half-life of insulin via inhibition of insulin degradation in the liver, interference with epinephrine-induced hyperglycemia via inhibition of glycogenolysis, and tetracycline-induced hepatotoxicity. The authors of one study suggest that tetracycline may also be able to inhibit alpha-amylase and/or alpha-glucosidase, as substrates for these enzymes have similar functional groups to those found in tetracycline. There are case reports available documenting hypoglycemia for patients on doxycycline and one case report demonstrating improved insulin sensitivity in a patient on minocycline. It is possible that other tetracyclines may possess similar abilities to lower glucose levels.

MANAGEMENT: Blood glucose should be monitored more closely during therapy with a tetracycline antibiotic. As the effects of the antibiotic may persist beyond the last dose, it is possible that patients may need to be monitored more closely until the antibiotic is fully eliminated from their body, which will differ depending on the half-life of the antibiotic involved. Insulin and insulin secretagogues may require dosage adjustments if an interaction is suspected. Patients should be apprised of the signs and symptoms of hypoglycemia (e.g., headache, dizziness, drowsiness, nausea, hunger, tremor, weakness, sweating, palpitations), how to treat it, and to contact their doctor if it occurs unexpectedly. Conversely, patients should be observed for loss of glycemic control following completion of tetracycline therapy.

Using bismuth subsalicylate together with tetracycline may decrease the effects of tetracycline. Administration of tetracycline and bismuth subsalicylate should be separated by two to three hours. If your doctor does prescribe these medications together, you may need a dose adjustment or special test to safely use 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.

Using bismuth subsalicylate together with insulin or certain other diabetes medications may increase the risk of hypoglycemia, or low blood sugar. Symptoms of hypoglycemia include headache, dizziness, drowsiness, nervousness, confusion, tremor, nausea, hunger, weakness, perspiration, palpitation, and rapid heartbeat. Talk to your doctor if you have any questions or concerns. You may need a dose adjustment or more frequent monitoring of your blood sugar to safely use 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.

Consumption of alcoholic beverages or products containing alcohol or propylene glycol during treatment with metroNIDAZOLE is not recommended. Doing so may occasionally trigger a reaction in some patients similar to the disulfiram reaction, which includes unpleasant effects such as flushing, throbbing in head and neck, throbbing headache, difficulty breathing, nausea, vomiting, sweating, thirst, chest pain, rapid heartbeat, palpitation, low blood pressure, dizziness, lightheadedness, blurred vision, and confusion. Rarely, more severe reactions may include abnormal heart rhythm, heart attack, heart failure, unconsciousness, convulsions, and even death. Patients treated with metroNIDAZOLE should continue to avoid using any products containing alcohol or propylene glycol for at least 3 days until after completion of therapy. Talk to your doctor or pharmacist if you have questions on how to take this or other medications you are prescribed. 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.

Do not take iron supplements, multivitamins, calcium supplements, antacids, or laxatives within 2 hours before or after taking tetracycline. These products can make tetracycline less effective in treating your infection. Do not take tetracycline with milk or other dairy products, unless your doctor has told you to. Dairy products can make it harder for your body to absorb the medication.

Alcohol may affect blood glucose levels in patients with diabetes. Both hypoglycemia (low blood sugar) and hyperglycemia (high blood sugar) may occur, depending on how much and how often you drink. You should avoid using alcohol if your diabetes is not well controlled or if you have high triglycerides, neuropathy (nerve damage), or pancreatitis. Moderate alcohol consumption generally does not affect blood glucose levels if your diabetes is under control. However, it may be best to limit alcohol intake to one drink daily for women and two drinks daily for men (1 drink = 5 oz wine, 12 oz beer, or 1.5 oz distilled spirits) in conjunction with your normal meal plan. Avoid drinking alcohol on an empty stomach or following exercise, as it may increase the risk of hypoglycemia. 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.

Iron can bind to tetracycline in the gastrointestinal tract, which may prevent their absorption into the bloodstream and possibly reduce their effectiveness. To avoid or minimize the interaction, iron-containing medications and tetracycline should preferably be taken at least three to four hours apart in most cases. Talk to your doctor if you have any questions or concerns, or if you have trouble separating the dosing times. Your doctor may be able to prescribe alternatives that do not interact. 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.