Once opened, a Follistim AQ Cartridge is good for 28 days. After that, any remaining medication should be discarded, even if the cartridge still contains usable volume. This 28-day window starts the moment a needle first pierces the rubber inlay of the cartridge, not from when you received it from the pharmacy.
The 28-Day Rule
The manufacturer is clear on this point: after the cartridge has been punctured, you have a maximum of 28 days to use the remaining medication. During that window, you can store the opened cartridge either in the refrigerator or at room temperature, as long as the temperature stays between 36°F and 77°F (2°C to 25°C). It does not need to be refrigerated once opened, but it does need to stay below 77°F.
Write the date of first use directly on the cartridge or its box so you don’t lose track. Fertility treatment cycles often involve daily injections over a span of days or weeks, and it’s easy to forget exactly when you started a cartridge.
Storage Before First Use
Unopened cartridges have more flexible storage rules. You can keep them refrigerated between 36°F and 46°F (2°C to 8°C) until the printed expiration date. If you prefer to store them at room temperature (up to 77°F), they remain stable for 3 months or until the expiration date, whichever comes first. Once you’ve taken the cartridge out of the fridge and stored it at room temperature, the 3-month clock starts ticking even if you haven’t opened it yet.
Two things to avoid with both opened and unopened cartridges: freezing and direct light. Either can damage the medication.
How to Tell if Follistim Has Gone Bad
Before every injection, look at the liquid inside the cartridge. Follistim should be completely clear and colorless, similar to water. If you notice any cloudiness, discoloration, or floating particles, do not use it. These changes can indicate the protein in the medication has degraded, which means it may not work properly and could cause irritation at the injection site.
Temperature abuse is the most common cause of degradation. If your cartridge was accidentally left in a hot car, exposed to direct sunlight for an extended period, or frozen, inspect it carefully before your next dose. When in doubt, replace it.
Using the Overfill
Follistim AQ Cartridges come in 300 IU, 600 IU, and 900 IU sizes, and each contains a small amount of overfill beyond the labeled volume. This extra medication is intentional. You should continue using each cartridge until it’s completely empty rather than discarding it once you’ve technically reached the labeled dose count. The overfill accounts for the small amount of liquid that can’t be expelled from the pen mechanism, ensuring you actually get the full labeled amount.
If you’re nearing the end of a cartridge and your prescribed dose is larger than what remains, you may need to split your dose between the old cartridge and a new one. Your clinic will walk you through how the Follistim Pen tracks remaining volume so you know exactly how much is left.
Traveling With an Opened Cartridge
Since opened Follistim is stable at room temperature up to 77°F, short trips in moderate weather don’t require special cooling. For longer travel or hot climates, pack the cartridge in a small insulated bag with a cold pack. Keep the medication in a waterproof case to prevent condensation damage, and avoid placing it directly against the ice pack, which could partially freeze the solution.
If you’re flying, carry Follistim and your pen supplies in your carry-on bag. Checked luggage compartments can reach freezing temperatures at altitude. Airport security generally allows injectable medications with a prescription label, but having your pharmacy label visible speeds things along.
What Happens After 28 Days
After 28 days, the sterility and potency of the medication can no longer be guaranteed. The rubber inlay that was pierced during first use creates a potential entry point for bacteria, and the protein-based hormone gradually loses effectiveness over time once exposed. Using expired Follistim likely won’t cause harm, but it may deliver a less potent dose, which in the context of a carefully timed fertility cycle could mean the difference between adequate and inadequate follicle stimulation. The cost of a compromised cycle far outweighs the cost of a replacement cartridge.