There are two main oral penicillin drugs: one is penicillin V potassium tablets; the other is amoxicillin, and the one with good effect is still amoxicillin. Penicillin V potassium tablets have a narrow antibacterial range and can kill a very limited variety of bacteria, and the resistance rate is relatively high, so it is less used now. Amoxicillin is a broad-spectrum penicillin antibiotic with a broader antibacterial range and is effective against both gram-stain-positive and gram-stain-negative bacteria. As amoxicillin is easily destroyed by β-lactamase produced by bacteria, thus losing its bactericidal effect, it is now often compounded with potassium clavulanate to form amoxicillin clavulanate for clinical application. Potassium clavulanate is responsible for controlling the β-lactamase produced by bacteria so that it cannot destroy amoxicillin, and amoxicillin can play its bactericidal role normally. In addition, amoxicillin is often combined with clarithromycin, metronidazole, and levofloxacin, plus other drugs that can work together to eradicate one particular bacterium, H. pylori.