Left your amoxicillin or Augmentin out of the refrigerator? It’s probably OK.
© 2014 Roy Benaroch, MD
We get these calls a few times a month—a family, despite dire warnings that their child’s antibiotic MUST be refrigerated, leaves it out on the counter overnight. Can we call in a new prescription?
Sure we can. But we probably don’t need to.
Many children’s antibiotics come in liquid suspensions. Little ground-up particles of medicine (along with flavorings and colorings and stabilizers and other goodies, collectively called “excipients”) are mixed by the pharmacist with water, and the bottle is shaken. Voila, you’ve got a suspension. But the water can break down some molecules especially if the water gets warm. So some of these suspensions are supposed to be kept in the ‘fridge, especially amoxicillin and amoxicillin/clavulanate (commonly called Augmentin.) That’s in the product insert: “keep refrigerated.” And it’s on a little sticker the pharmacist puts on the bottle. But is it really necessary?
Trust science to find out!
From The Journal of Applied Pharmaceutical Science, 2012, comes a study using state-of-the-art liquid chromotography to determine the potency of amoxicillin/clavulanate stored in three ways: refrigerated, stored in a cupboard at room temperature, and with the bottle submerged in water at room temperature (to minimize fluctuations in temperature.) Both the amoxicillin and clavulanate components of the medication kept all of their potency for at least five days. After that, there was a drop off in potency no matter how the samples were stored, though the refrigerated sample stayed the strongest. The amoxicillin portion of the medication lost about 17% of its potency in the fridge after 10 days, versus 25% of its potency in the cupboard. The clavulanate portion was a little bit more sensitive, losing about half of its potency at room temperature by day 7 to 10.
The study was done in Nigeria, where frequent power outages make consistent refrigeration problematic, and where limited resources make it more difficult to easily replace medications. But the results should be applicable here, too: under ordinary household circumstances, both amoxicillin and Augmentin are stable if left unrefrigerated for 5 days, maybe even longer for amoxicillin alone. They considered up to 84 degrees ordinary room temperature—again, this was in Nigeria. I imagine in typical cooler American homes these medications might last even longer sitting on the counter.
Some factors might further influence unrefrigerated shelf life. Light, especially direct sunlight, could potentially break down medications faster; and if the liquid gets really warm, left in a car, that’s going to ruin the medication pretty quickly. And this study only looked at two penicillin-based antibiotics (amoxicillin and Augmentin.) I can’t vouch for other medicines that are supposed to stay in the fridge. But it’s nice to know that for these common antibiotics, a few days at room temperature probably makes no difference.