BUD on a prescription label stands for Beyond-Use Date. It tells you the last date (or sometimes the last hour and date) you can safely use that medication. After the BUD, the pharmacy considers the preparation no longer reliable for use.
You’ll typically see a BUD on medications that were compounded, meaning a pharmacist mixed or prepared them specifically for you rather than dispensing a sealed manufacturer’s bottle. The date is calculated from the moment the pharmacist compounds the preparation, not from when you pick it up.
How a BUD Differs From an Expiration Date
A manufacturer’s expiration date applies to a sealed, mass-produced product and is based on extensive stability testing by the drug company. It can be years out. A BUD, on the other hand, applies to a preparation that was custom-mixed in a pharmacy. Because compounded medications haven’t undergone the same large-scale stability testing, their safe-use window is typically much shorter, sometimes days or weeks rather than months or years.
Both dates signal the same basic concern: after that point, the medication may lose potency, break down chemically, or become contaminated with bacteria. But a BUD is more conservative because there’s less data backing the stability of a one-off compounded preparation.
Why the BUD Matters for Safety
Once a pharmacist combines ingredients into a new formulation, the clock starts ticking on three risks: the active drug losing strength, the mixture degrading physically or chemically, and microbes growing in the preparation. These risks are especially relevant for liquid medications, creams, and anything that contains water, since moisture creates an environment where bacteria can multiply.
Potency loss is more than a theoretical problem. Antibiotics that have lost strength may not fully clear an infection, and using sub-potent antibiotics can contribute to antibiotic resistance. Medications with a narrow margin between an effective dose and an ineffective one are particularly sensitive to even small drops in potency. Injectable medications that look cloudy, discolored, or contain visible particles should never be used regardless of the date on the label.
What Determines the Length of a BUD
The United States Pharmacopeia (USP) sets the standards pharmacies follow when assigning BUDs. Separate chapters cover sterile preparations (like IV bags and injectable solutions) and nonsterile preparations (like oral suspensions, capsules, and topical creams). The updated USP General Chapter 795 for nonsterile compounding became official on November 1, 2023.
Several factors influence how long a compounded medication stays stable:
- Whether it contains water. Water-containing liquids like oral suspensions spoil faster than dry formulations like capsules or powders.
- Storage temperature. Refrigeration slows both chemical breakdown and microbial growth, so refrigerated preparations often get a longer BUD than those kept at room temperature (defined by USP as 20°C to 25°C, or about 68°F to 77°F).
- The container it’s dispensed in. The packaging needs to protect the preparation from air, light, and contamination. A preparation in a less protective container may get a shorter BUD.
- Light and humidity exposure. Some active ingredients degrade when exposed to light or moisture, which can prompt a pharmacist to shorten the default BUD.
If the pharmacy has done its own stability testing or can rely on published data for a specific formulation, it may assign a longer BUD. Without that evidence, pharmacists default to the conservative limits set by USP standards.
Where to Find the BUD on Your Label
The BUD is usually printed directly on the prescription label, often near the dispensing date. For sterile compounded preparations, the label may include both a date and a specific time, since some of these products are only stable for hours. For nonsterile preparations like a compounded cream or oral liquid, you’ll typically see just a date.
Don’t confuse the BUD with the date the prescription was filled. The fill date tells you when the pharmacy dispensed it. The BUD tells you when to stop using it. If your label shows only one date and you’re unsure which it is, your pharmacist can clarify.
What to Do When a Medication Passes Its BUD
Stop using the medication once the BUD has passed, even if it looks and smells fine. Chemical degradation and early microbial contamination aren’t always visible. This is especially important for liquid preparations, reconstituted suspensions (like liquid antibiotics mixed with water), and anything that’s been refrigerated.
Unintentional temperature changes can also compromise a medication before its BUD. If a preparation that requires refrigeration was left out for an extended period, perhaps during a power outage, transport delay, or simply being forgotten on a counter, it may no longer be safe to use even if the date hasn’t passed.
For disposal, the FDA recommends using a drug take-back program as the preferred option. Many pharmacies and community organizations host take-back locations, and some offer prepaid mail-back envelopes. A small number of medications appear on the FDA’s flush list, meaning they should be flushed down the toilet to prevent accidental ingestion by children or pets. For everything else not on the flush list, the FDA provides home disposal instructions that typically involve mixing the medication with coffee grounds or kitty litter in a sealed container before placing it in household trash.