Key takeaways
Metronidazole (Flagyl) and doxycycline hyclate (Vibramycin, Doryx) are both antibiotics used to treat bacterial infections, but they belong to different medication classes. Metronidazole is a nitroimidazole antibiotic, while doxycycline hyclate is a tetracycline antibiotic. Both medications can treat sexually transmitted infections (STIs), but doxycycline hyclate is also used for conditions like acne, respiratory infections, and urinary tract infections (UTIs), which are not treated by metronidazole. Metronidazole is typically taken three times a day, whereas doxycycline hyclate is usually taken once or twice daily. Both medications are available as a lower-cost generic. Metronidazole should not be taken with alcohol due to serious interactions, while doxycycline hyclate does not have this restriction but can cause sun sensitivity. Common side effects of metronidazole include nausea and a metallic taste, while doxycycline hyclate can cause stomach upset and sunburn. Both medications can interact with blood thinners, but metronidazole also interacts with disulfiram and lithium, whereas doxycycline hyclate can affect birth control effectiveness.
