When does Doxycycline become toxic?
In the case of doxycycline, there has been an historical tendency to include the same warnings that are included for tetracycline. While doxycycline is part of the same family of antibiotics as tetracycline it shares some very important differences. Among those differences is that it DOES NOT degrade to any toxic components over time. In fact, this is one of the main reasons it was included in the kit. The antibiotics in your kit have been very thoughtfully put together by a panel of experts in their field. Including physicians and pharmacists.
“Stability studies reviewed by FDA over many years have confirmed that none of the components of approved doxycycline tablets and capsules, including the active ingredient, has significant potential for chemical degradation or interaction with other components in the formulation or with components of the container closure system when stored according to labeled directions… Based on historical data, doxycycline tablets and capsules are expected to remain within USP assay and dissolution acceptance criteria beyond their labeled expiration dates.” -Extending Expiration Dates of Doxycycline Tablets and Capsules in Strategic Stockpiles, Draft Guidance for Government Public Health and Emergency Response Stakeholders.