Severe. These medicines may interact and cause very harmful effects and are usually not taken together. Contact your healthcare professional (e.g. doctor or pharmacist) for more information.
How the interaction occurs:
Metronidazole and tinidazole cause an intolerance to alcohol by altering how the body breaks down alcohol. Many medicines (prescription and nonprescription), mouthwashes, and aftershaves contain alcohol. Even a small amount of alcohol (e.g. 15 ml or one tablespoon) can trigger the effects.
What might happen:
Ingesting alcohol or using topical preparations that contain alcohol may result in throbbing in the head and neck, irregular heart beat, rapid heart beat, low blood pressure, sweating, nausea, and vomiting. This interaction may last from 30 to 60 minutes to several hours, depending on the amount of alcohol consumed.
What you should do about this interaction:
If possible, avoid the use of medicines that contain alcohol when using metronidazole. Use of topical products such as creams or lotions that contain alcohol may also cause this interaction. The amount of alcohol required to cause this interaction varies with individuals.If you are using metronidazole with a product that contains alcohol, or if you notice signs or symptoms of this interaction, contact your healthcare professional (e.g. doctor or pharmacist). Your doctor may want to do blood tests or make changes to your medicines.If you are taking tinidazole, avoid alcoholic beverages and products containing alcohol while you are taking tinidazole and for 3 days after you finish taking tinidazole.Your healthcare professionals may already be aware of this interaction and may be monitoring you for it. Do not start, stop, or change the dosage of any medicine before checking with them first.
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