Doctors give trusted answers on uses, effects, side-effects, and cautions: Dr. POMERANCE on is omnicef a strong antibiotic: 'strong' or 'weak.' there is broad or narrow spectrum; there is high or low toxicity to humans; and there is the question of whether this antibiotic is right for this infection or not. Cipro (ciprofloxacin) is broad. Pictures of Keflex (Cephalexin), drug imprint information, side effects for the patient. Keflex is a cephalosporins drug and there have been instances of cross allergies between the two drugs. If you are allergic to penicillin it is usually best to avoid Keflex too. What is cephalexin used for? This eMedTV page explains that this prescription antibiotic can treat bacterial infections and prevent heart valve infections. It can also be a substitute for penicillin if a person is allergic to that particular drug. Doxycycline uses are primarily for the treatment of bacterial and anthrax infections, malaria, and acne. This eMedTV page explains how the drug can also prevent malaria and treat infections that are resistant to another antibiotic called vancomycin. Medical Disclaimer Next Side Effects Add to My Med List More about Keflex (cephalexin) Consumer resources Other brands: get keflex fast Biocef, Daxbia Professional resources Related treatment guides. Keflex is a cephalosporin (SEF a low spor in) antibiotic. It works by fighting bacteria in your body. Keflex is used to treat infections caused by bacteria, including upper respiratory infections, ear infections, skin infections, urinary tract infections, and bone infections. What should I discuss with my healthcare provider before taking cefdinir (Omnicef, Omnicef Omni-Pac)? Do not take this medication if you are allergic to cefdinir or to other cephalosporin antibiotics, such as: Cefdinir and Alcohol. Cefdinir can bring on drowsiness or dizziness, and drinking alcohol can intensify these side effects. Cefdinir and Drug Interactions Cefdinir is taken once or twice daily, depending on the type and severity of the infection. The capsules or suspension can be taken with or without food.