Menopur has an elimination half-life of 11 to 13 hours, meaning a single dose is mostly cleared from your bloodstream within about two to three days. After your last injection in a treatment cycle, residual levels typically become negligible within roughly 3 days, though the hormonal effects on your ovaries can persist longer than the drug itself.
How Menopur Moves Through Your Body
Menopur contains two fertility hormones: follicle-stimulating hormone (FSH) and luteinizing hormone (LH). After a subcutaneous injection, these hormones absorb slowly. Blood levels of FSH peak around 18 hours after the shot, which is notably slower than many injectable medications. This slow absorption is part of why the drug’s effects feel gradual rather than immediate.
Once in your bloodstream, FSH from Menopur has a half-life of 11 to 13 hours regardless of whether you inject subcutaneously (into belly fat) or intramuscularly. A half-life is the time it takes for half the drug to be eliminated. After five half-lives, a drug is considered essentially gone. For Menopur, that works out to roughly 55 to 65 hours, or about two and a half to three days after your final injection.
What Happens With Repeated Daily Injections
During a typical stimulation cycle, you inject Menopur daily for several days in a row. Because you’re adding a new dose every 24 hours while the previous dose hasn’t fully cleared, the drug accumulates in your system. Clinical data from the FDA review shows about a 1.3-fold increase in peak levels at steady state and a 3-fold increase in overall exposure compared to a single dose. This accumulation is expected and is part of how the medication builds up enough hormonal stimulation to mature multiple follicles.
This stacking effect means clearance after your last injection in a multi-day cycle takes slightly longer than it would after a single shot. Still, because the half-life doesn’t change with repeated dosing, the timeline remains in the same ballpark: most of the drug will be out of your blood within about three days of stopping.
Drug Clearance vs. Hormonal Effects
There’s an important distinction between how long the medication itself circulates and how long its effects last. Menopur stimulates your ovaries to grow follicles, and once those follicles are developing, they produce their own estrogen and progesterone. Those hormonal changes don’t stop the moment Menopur clears your blood. Your ovaries continue responding to the stimulation they’ve already received, which is why egg retrieval is typically scheduled a couple of days after your last gonadotropin injection.
If you’re wondering whether leftover Menopur could affect a pregnancy test or an hCG trigger shot, the answer is that Menopur itself doesn’t contain hCG and shouldn’t cause a false positive on a pregnancy test. However, the LH component in Menopur is structurally similar to hCG, so if you’re testing very soon after your last dose, there’s a small theoretical possibility of cross-reactivity on very sensitive assays. In practice, most clinics time blood work and urine tests with this clearance window in mind.
Factors That Might Affect Clearance
You might expect that body weight, age, or kidney function would change how fast Menopur leaves your system. The FDA reviewed these potential variables during the drug’s approval process and found no meaningful connection between patient characteristics and FSH clearance rates. The initial analyses that suggested age or BMI might matter turned out to be statistical noise. Based on available data, the 11-to-13-hour half-life holds fairly consistently across patients.
That said, the formal studies were conducted in relatively small groups, and the effects of significant kidney or liver impairment on Menopur clearance have never been specifically studied. The drug’s metabolism in humans hasn’t been fully characterized either, so exactly which organs break it down remains unclear. What is known is that FSH and LH are proteins, and like other protein hormones, they’re likely broken down by the kidneys and liver through normal protein recycling pathways.
Practical Timeline After Your Last Dose
Here’s a simplified breakdown of what to expect after your final Menopur injection:
- 0 to 18 hours: Drug levels are still rising as the injection site continues releasing medication into your bloodstream.
- 18 to 30 hours: Blood levels peak and begin to decline.
- 2 to 3 days: The vast majority of the drug has been eliminated. Circulating levels drop below meaningful thresholds.
If you’ve been injecting daily for a week or more, the accumulated drug takes the same general path but starts from a higher baseline. Even so, you can expect most of it to clear within three days of your last injection. Your fertility clinic schedules monitoring bloodwork and procedures around this clearance timeline, so the timing of your trigger shot and retrieval already accounts for how long Menopur lingers.