Final answer:
To ensure safe and effective medication, patients taking Metronidazole and Tinidazole for STIs should avoid alcohol completely during and after the medication period.
Step-by-step explanation:
Patients taking Metronidazole and Tinidazole for STIs should avoid alcohol completely during the medication period and 48 hours after. This is because both Metronidazole and Tinidazole can interact with alcohol and cause unpleasant side effects such as flushing, nausea, dizziness, sweating, headache, and low blood pressure.