Menopur works by delivering follicle-stimulating hormone (FSH) and luteinizing hormone (LH) directly into your body, telling your ovaries to grow multiple follicles — each one a potential egg — instead of the single egg your body would normally produce each month.

What Menopur Does in Your Body

In a natural menstrual cycle, your pituitary gland releases small amounts of FSH and LH. FSH tells your ovaries to start growing follicles, and LH helps those follicles mature and eventually triggers ovulation. Usually, only one follicle becomes dominant and releases a single egg.

Menopur changes this by flooding your system with higher-than-normal levels of both FSH and LH. Here's what each hormone does:

• FSH (follicle-stimulating hormone) — Stimulates multiple ovarian follicles to grow at the same time, rather than just one. This is the primary driver of Menopur's effect.
• LH (luteinizing hormone) — Supports the theca cells surrounding each follicle, which produce androgens that get converted into estrogen. This estrogen helps the follicles and the uterine lining develop properly.

The combination of FSH and LH is what makes Menopur different from medications like Gonal-F or Follistim, which contain only FSH. Some doctors believe the added LH activity in Menopur produces better egg quality in certain patients, though this is still debated in the medical literature.

Menopur is classified as a human menopausal gonadotropin (hMG) because it's derived from the urine of postmenopausal women, whose bodies naturally produce high levels of these hormones.

How Long Does Menopur Take to Work?

Menopur doesn't work overnight. Here's a general timeline:

• Days 1-3: You begin daily injections. Your ovaries start responding, but follicles are still very small.
• Days 4-6: Follicles begin growing measurably. Your doctor starts monitoring with ultrasounds and blood tests to check estradiol levels.
• Days 7-10: Follicles reach measurable sizes (typically 10-18mm). Your doctor may adjust your Menopur dose up or down based on response.
• Days 10-12: Lead follicles reach 18-22mm, indicating they contain mature eggs. Your doctor triggers ovulation with an hCG injection (the "trigger shot").

The total stimulation period is typically 5 to 12 days, with most patients stimulating for 8 to 10 days. Everyone responds differently — your age, ovarian reserve, and protocol all affect the timeline.

Your fertility team monitors you closely throughout this process. If you're responding too slowly, they'll increase your dose. If you're responding too aggressively (raising your risk of OHSS), they'll lower it or consider coasting.

How Long Does Menopur Last in Your System?

Each Menopur injection provides hormones that are active for roughly 24 hours, which is why you take it once daily at the same time. After your last injection, the hormones clear your system relatively quickly — within a couple of days.

However, the effects of Menopur — the enlarged follicles and elevated estrogen levels — persist longer. Your ovaries may remain enlarged for a week or more after egg retrieval, and OHSS symptoms (if they develop) can last even longer, especially if pregnancy occurs.

What Makes Menopur Different From Other Fertility Drugs?

There are several gonadotropins used in fertility treatment. Here's how Menopur compares:

• Menopur vs. Gonal-F / Follistim — Gonal-F and Follistim are recombinant (lab-made) FSH-only medications. Menopur is urinary-derived and contains both FSH and LH. Some protocols use Menopur alone; others combine it with a recombinant FSH product.
• Menopur vs. Pergoveris — Pergoveris is also a combination FSH/LH product, but it's recombinant rather than urinary-derived. It's the closest pharmacologic match to Menopur among recombinant options.
• Menopur vs. Clomid / Letrozole — Clomid and Letrozole are oral medications that work indirectly by affecting estrogen signaling. They're much milder than Menopur and typically used for simpler ovulation induction, not IVF.

Your doctor chooses Menopur based on your specific situation — your hormone levels, ovarian reserve, age, and the type of cycle you're doing. To learn more about the basics, see What Is Menopur?

Final Thoughts

Menopur works by giving your ovaries a controlled boost of FSH and LH — the same hormones your body produces naturally, just in higher amounts. This stimulates multiple follicles to grow at once, giving your fertility team more eggs to work with during IVF or improving your chances during an IUI cycle.

If you're about to start Menopur and need help finding it, check Medfinder to see which pharmacies near you have it in stock.