Updated: Jul 25, 2020
Penicillins describe a whole set of medications including penicillin V, amoxicillin, cloxacillin and amoxicillin/clavulanate.
Penicillin V: strep throat [drug of choice]
Amoxicillin: pneumonia, strep throat, dental surgery, otitis media, asymptomatic bacteriuria in pregnancy
Cloxacillin: impetigo, skin infections, Staphylococcus aureus infections
Amoxicillin/clavulanate: broad spectrum antibiotic for severe infections; contains clavulanate to overcome beta-lactamase resistance
Common to all: nausea, vomiting, diarrhea, may lower seizure threshold, allergic reaction
Adverse effects are more common with broad spectrum amoxicillin/clavulanate due to the clavulanate portion.
All safe in pregnancy.
Penicillin: with or without food
Amoxicillin: with food generally better. High dose regimen recommended for otitis media and pneumonia. This overcomes Strep pnuemoniae resistance, but at the expense of more adverse effects.
Cloxacillin: on empty stomach
Amoxicillin/clavulanate: with food. Two formulations available: 7:1 and 4:1 ratios. Generally, 7:1 is dosed twice daily, whereas 4:1 is dosed three times daily.