Follitropin beta
Recombinant follicle-stimulating hormone for ovulation induction and IVF, sold as Follistim and Puregon
Follitropin beta is recombinant human FSH, the pituitary hormone that grows ovarian follicles, used to induce ovulation and to stimulate several follicles for IVF. Organon's Follistim was first approved in the US on September 29, 1997; the current form is Follistim AQ Cartridge, dosed with a pen.
What is it?
Follicle-stimulating hormone grows ovarian follicles in women and supports sperm production in men. Follitropin beta is the recombinant form made in cell culture by Organon, sold as Follistim in the US and Puregon elsewhere, and acts on the FSH receptor exactly as follitropin alfa does. The label gives a half-life of 33.4 hours after a single 150 IU dose.
Before recombinant FSH, clinics used hormone purified from the urine of post-menopausal women. The comparison trials of the 1990s found recombinant follitropin beta retrieved more eggs from a lower total dose than urinary FSH (10.84 against 8.95), with pregnancy rates the same or somewhat higher, and it did at least as well as human menopausal gonadotropin. Against follitropin alfa, IVF outcomes were alike (clinical pregnancy 29.1% and 28.1%).
Dose has limits. In IVF, starting at 200 IU rather than 100 IU for the first four days added about one egg, not a significant difference, at a 36% higher total dose. In women in their thirties, raising a fixed dose from 150 to 250 IU helped only those aged 30 to 33; for women 37 to 39 a higher dose did not compensate for age.
For ovulation induction, as in clomiphene-resistant polycystic ovary syndrome, the label starts low (50 IU) and steps up weekly. In one series every woman responded, but four of the cycles were cancelled for overstimulation, which is why that protocol is monitored closely.
The US label also covers men with hypogonadotropic hypogonadism. In a randomised study of men still without sperm after hCG alone, adding follitropin beta for 48 weeks brought sperm into the ejaculate in 47%, after a median of about five and a half months.
Delivery has changed with it: the current Follistim AQ Cartridge is given with a pen, and in a blinded crossover study the pen caused moderate or severe pain at injection far less often than a conventional syringe of follitropin alfa (21.7% against 70.0%). Longer-acting relatives now exist; a single dose of corifollitropin alfa matched a week of daily follitropin beta in poor responders.
The label's risks are those of every gonadotropin: ovarian enlargement and hyperstimulation syndrome, twisting of an ovary, blood clots in the lungs and veins, ectopic pregnancy and multiple pregnancy, which is why stimulation is monitored with ultrasound and estradiol.
Mechanism of Action
Follitropin beta is FSH itself, made recombinantly: it drives follicle growth in the ovary and sperm production in the testis.
FSH receptor
Activates the FSH receptor on granulosa cells, as follitropin alfa does (dataset mechanism).
Follicle recruitment
Recruits and matures follicles during ovulation induction or controlled ovarian stimulation (dataset mechanism).
Daily dosing
Half-life 33.4 hours after a single 150 IU dose (Follistim AQ label 12.3).
Published Research
The trials behind follitropin beta, read from their PubMed abstracts: comparisons with urinary FSH, hMG, follitropin alfa and corifollitropin alfa, dose studies in IVF, ovulation induction in PCOS, treatment of men, and a pen tolerability study. Dosing from the Follistim AQ label read October 1, 2026.
Against urinary FSH
In a multicentre IVF trial, recombinant FSH retrieved more oocytes than urinary FSH (10.84 against 8.95) from a lower total dose; ongoing pregnancy per attempt was 22.2% against 18.2%, not significant, and 25.7% against 20.4% counting frozen embryos.
Against hMG
Against human menopausal gonadotropin, ongoing pregnancy per started cycle was 22.2% against 17.1% and implantation 27.5% against 16.7%, with similar total doses (1,410 against 1,365 IU).
Against follitropin alfa
Comparing Gonal-F with Puregon in IVF, stimulation outcomes did not differ and clinical pregnancy rates were 29.1% and 28.1%.
Against purified urinary FSH
Bravelle, a highly purified urinary FSH, matched Follistim in controlled ovarian hyperstimulation for IVF, with no difference in adverse events, though its injections were reported as less painful.
Against corifollitropin in poor responders
In 79 proven poor responders, a single 150 µg dose of corifollitropin alfa was non-inferior to daily 450 IU follitropin beta for the first week (median 3 against 2 oocytes), with no significant difference in live birth.
Starting dose: 100 or 200 IU
In a double-blind IVF trial, starting follitropin beta at 100 or 200 IU for the first four days retrieved 10.9 and 12.2 oocytes (not significant) from total doses of 1,887 and 2,559 IU, with similar embryos, pregnancies, cancellations and OHSS.
Age limits what dose can do
In 138 women aged 30 to 39, a fixed 250 IU daily dose retrieved 10.6 oocytes against 9.1 on 150 IU (not significant); the extra yield was confined to women 30-33 (14.8 against 10.6), while women 37-39 gained nothing.
Low-dose step-up in PCOS
In women with clomiphene-resistant polycystic ovary syndrome, a low-dose step-up protocol starting at 50 IU produced follicles in all; six ovulated and two conceived, while four cycles were cancelled for overstimulation.
Inducing sperm production in men
In 30 men with hypogonadotropic hypogonadism who stayed azoospermic after 16 weeks of hCG, adding recombinant FSH (225 IU twice or 150 IU three times weekly) for 48 weeks induced sperm counts of at least 1 million/mL in 14 (47%), after a median of about 5.5 months.
Pen against syringe: injection pain
In a blinded crossover study of 60 healthy women, moderate to severe pain at injection was reported by 21.7% with the follitropin beta pen against 70.0% with follitropin alfa by conventional syringe.
Dosing Data
Dosed by label and adjusted to follicle growth and estradiol; hCG triggers final egg maturation.
Educational information, not medical advice. Each dose above is tagged with its source: an approved label, a published human study, animal data, or amounts reported by users. None is a recommendation for you. An unapproved compound has no established safe or effective human dose, and products sold for “research use only” are not made or tested for people. Talk to a doctor before acting on anything on this site, including before you start, stop or change any medicine or dose. Full medical disclaimer.
Side Effects & Contraindications
Reported Side Effects
From the Follistim AQ label (version 11).
Contraindications & Cautions
From the label.
Legal Status
Approved in the US since 1997.
Frequently Asked Questions
?Are Follistim and Puregon the same?
Yes: both are follitropin beta from Organon, Follistim in the US and Puregon elsewhere.
?Is it better than follitropin alfa?
Head-to-head IVF comparisons such as the 2000 trial found no difference in outcomes.
?Is it used in men?
Yes: the US label includes dosing to induce sperm production in men with hypogonadotropic hypogonadism, with another hormone given alongside.
?Does a higher dose mean more eggs?
Only up to a point: starting at 200 rather than 100 IU added about one egg, not significantly, and in women 37 to 39 a higher dose did not compensate for age.
?How is it used for ovulation induction?
The label starts at 50 IU and increases weekly as needed, with close monitoring because overstimulation can cancel a cycle.
?Does it work in men?
With hCG, it induced sperm production in 47% of men with hypogonadotropic hypogonadism after 48 weeks in one randomised study.
?Is the pen less painful?
In a blinded crossover study, moderate or severe injection pain occurred in 21.7% with the follitropin beta pen against 70.0% with a follitropin alfa syringe.
?What is the main risk?
Ovarian hyperstimulation syndrome, along with multiple pregnancy, which is why stimulation is monitored with ultrasound and estradiol.
References
- [fda-pi] Follistim AQ Cartridge (follitropin beta) injection US prescribing information (DailyMed version 11, effective May 26, 2026); read October 1, 2026.
- [clinical-trial] Out HJ, et al. "A prospective, randomized, assessor-blind, multicentre study comparing recombinant and urinary follicle stimulating hormone (Puregon versus Metrodin) in in-vitro fertilization." Hum Reprod, 1995;10(10):2534-40. PMID: 8567765.
- [clinical-trial] Jansen CA, et al. "A prospective randomized clinical trial comparing recombinant follicle stimulating hormone (Puregon) and human menopausal gonadotrophins (Humegon) in non-down-regulated in-vitro fertilization patients." Hum Reprod, 1998;13(11):2995-9. PMID: 9853844.
- [clinical-trial] Harlin J, et al. "Recombinant follicle stimulating hormone in in-vitro fertilization treatment-clinical experience with follitropin alpha and follitropin beta." Hum Reprod, 2000;15(2):239-44. PMID: 10655291.
- [clinical-trial] Dickey RP, et al. "Highly purified human-derived follicle-stimulating hormone (Bravelle) has equivalent efficacy to follitropin-beta (Follistim) in infertile women undergoing in vitro fertilization." Reprod Biol Endocrinol, 2003;1:63. PMID: 14609434.
- [clinical-trial] Tan SL, et al. "A randomized, double-blind, multicenter study comparing a starting dose of 100 IU or 200 IU of recombinant follicle stimulating hormone (Puregon) in women undergoing controlled ovarian hyperstimulation for IVF treatment." J Assist Reprod Genet, 2005;22(2):81-8. PMID: 15844733.
- [clinical-trial] Out HJ, et al. "Increasing the daily dose of recombinant follicle stimulating hormone (Puregon) does not compensate for the age-related decline in retrievable oocytes after ovarian stimulation." Hum Reprod, 2000;15(1):29-35. PMID: 10611184.
- [pubmed] Hayden CJ, et al. "Induction of ovulation with the use of a starting dose of 50 units of recombinant human follicle-stimulating hormone (Puregon)." Fertil Steril, 1999;71(1):106-8. PMID: 9935125.
- [clinical-trial] Bouloux PM, et al. "Induction of spermatogenesis by recombinant follicle-stimulating hormone (puregon) in hypogonadotropic azoospermic men who failed to respond to human chorionic gonadotropin alone." J Androl, 2003;24(4):604-11. PMID: 12826700.
- [clinical-trial] Craenmehr E, et al. "Follitropin-beta administered by pen device has superior local tolerance compared with follitropin-alpha administered by conventional syringe." Reprod Biomed Online, 2001;3(3):185-189. PMID: 12513852.
- [clinical-trial] Kolibianakis EM, et al. "Corifollitropin alfa compared with follitropin beta in poor responders undergoing ICSI: a randomized controlled trial." Hum Reprod, 2015;30(2):432-40. PMID: 25492411.
Sources & Citations
Dosing and warnings from the Follistim AQ Cartridge label (DailyMed version 11, effective May 26, 2026, read October 1, 2026); approvals from Drugs@FDA; studies from PubMed abstracts.
Medical Disclaimer: This content is for educational and informational purposes only. It is not medical advice, and nothing here is an instruction to obtain or use any compound. Talk to a licensed clinician about your own situation.