Fertility Glossary

GnRH agonist

A medication that first stimulates then suppresses the pituitary.

Medicines & protocols

Agonists cause an initial flare of FSH and LH before down-regulating the pituitary. They are used for long protocols, for suppression in endometriosis, and as an OHSS-sparing trigger.

Also known as: leuprolide, buserelin, nafarelin, Lupron

Related Canada guides

IVF medications in Canada: what each medicine is used for
IVF stimulation protocols: antagonist, long agonist and other approaches

Sources

Canadian Fertility and Andrology Society (CFAS)

Last reviewed: September 9, 2026. Written by the Antega Editorial Team. General information only — always follow the advice of your own clinic, doctor or pharmacist.

Related terms

Long agonist protocol

An older IVF protocol that suppresses the pituitary before stimulation begins.

Agonist trigger

A GnRH agonist used instead of hCG to mature eggs and cut OHSS risk.

Endometriosis

Endometrial-like tissue growing outside the uterus.

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