Cefexta 300 mg contains Cefdinir, a third-generation cephalosporin antibiotic that is used to treat a variety of bacterial infections. It works by inhibiting the synthesis of the bacterial cell wall, ultimately leading to the destruction of the bacteria. Cefexta is effective against a wide range of Gram-positive and Gram-negative bacteria and is commonly used to treat infections in the respiratory tract, skin, and urinary tract.