Amoxicillin + clavulanic acid

The clavulanate half makes this drug more likely to cause serious liver injury than amoxicillin alone, and the benefit over a shorter, narrower antibiotic depends entirely on whether the infection is resistant.

Amoxicillin plus clavulanic acid (Augmentin) is an antibiotic for bacterial infections like pneumonia, sinusitis, and ear infections. The clavulanate part is a beta-lactamase inhibitor—it blocks an enzyme that some bacteria use to destroy amoxicillin. This broadens the coverage beyond plain amoxicillin, but at a cost.

The most important safety signal is liver damage. Italian spontaneous reporting data showed that the combination caused 4% of all reported adverse reactions, and those liver injuries were flagged as serious [2]. By comparison, plain amoxicillin caused only 1% liver reactions and none were labeled serious [2]. In a U.S. prospective cohort of drug-induced liver injury cases, amoxicillin-clavulanate was the single most common cause—23 out of 300 cases, more than any other drug [1]. That is a real and documented risk, not a rare curiosity.

The benefit is real but modest and situational. In a large placebo-controlled trial of children with acute otitis media, amoxicillin-clavulanate cut treatment failure from 44.9% to 18.6%—meaning about 1 in 4 children avoided a failed course [4]. But almost half the children on the drug developed diarrhea (77 of 161) compared to 27% on placebo [4]. For adult sinusitis, the numbers needed to treat with any antibiotic for one symptom improvement range from 7 to 18, while 27% of antibiotic users report adverse effects versus 15% on placebo [5]. Most sinusitis and ear infections are viral or self-limiting, so much of that antibiotic use is unnecessary.

When the organism is sensitive, plain amoxicillin works as well and carries less liver and diarrhea risk. The combination should be reserved for confirmed beta-lactamase-producing infections—not used as a first-line default.

My call: Use only when a culture or strong clinical evidence shows resistance to plain amoxicillin. For routine sinusitis, otitis, or bronchitis, the risk of liver injury and gut disruption outweighs the marginal benefit. Confidence: high for the safety profile (liver injury is well-documented in multiple registries), moderate for the comparative effectiveness (many trials compare to other antibiotics, not to no treatment).