When Does Amoxicillin Suspension Expire?

In our latest question and answer, the pharmacist discusses why amoxicillin suspension expires after 14 days.

Question

Why can't you use amoxicillin suspension after 14 days?

Asked by jojo On May 09, 2019

Answered by
Medical Content Reviewed By PharmacistAnswers Staff

On May 10, 2019
Pouring White Reconstituted Antibiotic with text - Amoxicillin Suspension Expire After 14 Days?

Overview

Amoxicillin suspension products expire 14 days after it has been reconstituted by the pharmacist.[1]

This 14-day expiration date applies for all strengths of amoxicillin suspension, which include:

  • 125 mg/5mL
  • 200 mg/5mL
  • 250 mg/5mL
  • 400 mg/5mL

It is important to differentiate between the expiration date of the un-reconstituted suspension (which is simply the powder in the bottle) and the reconstituted suspension (when the powder is mixed with water).

Un-reconstituted amoxicillin powder has a much longer shelf-life, typically over a year from manufacture.

It is only when the amoxicillin powder is mixed with water that the expiration date decreases to only 14 days.


Why 14-Days?

The 14-day expiration date on amoxicillin suspension products is the manufacturer listed date based on stability data for the product.

Per the prescribing information for one amoxicillin suspension product:[2]

Keep bottle tightly closed. Any unused portion of the reconstituted suspension must be discarded after 14 days. Refrigeration is preferable, but not required.
Amoxil Prescribing Information

So, regardless of whether or not amoxicillin suspension is refrigerated, it is only good for 14 days. Refrigeration is recommended as it tends to improve the overall taste of the liquid.

After 14 days, it should be thrown out and not used.

This 14-day expiration date is based on the stability data for the drug. Stability testing shows that after 14 days, the drug may have degraded to the point where it not may be as effective as it once was, increasing the risk of treatment failure.[3]

Additionally, while amoxicillin suspensions do contain a preservative (sodium benzoate), they are more susceptible to contamination the longer they are from removed from their initial mixing date.

Numerous studies show that the 14-day expiration date of reconstituted (i.e. mixed) amoxicillin products is not simply a conservative recommendation, but warranted based on how quickly the drug degrades. It degrades even faster if stored in unit-dose oral syringes.[4][5][6]

Other reconstituted products that contain amoxicillin, such as amoxicillin/clavulanate products (generic Augmentin), expire more quickly, 10 days after reconstitution.[7]


More Than 14-Day Therapy?

An issue that arises for some individuals is what to do if your prescribed therapy of amoxicillin is over 14 days since you cannot have more than 14-days of product mixed up at one time (due to the expiration).

If you have been prescribed amoxicillin suspension for more than a 14-day time period, you will need to return to your pharmacy and have the pharmacist mix another bottle for you when it comes time to continue your therapy.

While policies differ by the pharmacy (and state law), generally, your pharmacy will store any product you can't pick up right away at the pharmacy and mix it when appropriate. It is uncommon that they would let you take home a powder of amoxicillin powder that has yet to be reconstituted.

While it certainly isn't difficult to mix water with the powder to make the resulting suspension, pharmacies have specific measuring devices to ensure that the exact amount of water is added to the product to make the required concentration (e.g. 250mg/mL).

Home measuring devices (e.g. teaspoons, measuring cups) aren't precise enough and could result in an amoxicillin suspension that is either under-concentrated or over-concentrated.


Summary

Amoxicillin suspensions expire after 14 days. After 14 days, there is the risk that the product has degraded to the point where it won't be as effective as it once was, potentially leading to treatment failure.

References
  1. ^ Elsevier ClinicalKey: Amoxicillin Monograph. ClinicalKey
  2. ^ Amoxil Prescribing Information. AccessFDA
  3. ^ ToxNET: Amoxicillin. ClinicalKey
  4. ^ The stability of amoxicillin trihydrate and potassium clavulanate combination in aqueous solutions. PubMed
  5. ^ Stability of amoxicillin in portable pumps is drug concentration dependent. PubMed
  6. ^ Stability of oral liquid penicillins in unit dose containers at various temperatures. PubMed
  7. ^ Augmentin Prescribing Information. AccessFDA

About the Pharmacist

Dr. Brian Staiger Pharm.D

Dr. Brian Staiger is a licensed pharmacist in New York State and the founder of PharmacistAnswers.com. He graduated from the University At Buffalo with a Doctor of Pharmacy degree in 2010. He has been featured in numerous publications including the Huffington Post as well as a variety of health and pharmacy-related blogs. Please feel free to reach out to him directly if you have any inquiries or want to connect! He's answered thousands of medication and pharmacy-related questions and he's ready to answer yours! Brian.Staiger@PharmacistAnswers.com Office: 716-389-3076

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