IVF Medications Explained — What Each Injection Actually Does

IVF involves several different medications, each with a specific role. Understanding what each one does, why your protocol uses it, and what side effects to expect makes the cycle less mysterious and more manageable. This page explains the major classes.

1. FSH — the stimulator

Follicle-stimulating hormone (FSH) drives multiple follicles to develop simultaneously. Brand names: Gonal-F, Puregon (recombinant FSH), Menopur (FSH+LH mix). Dose varies (75–450 IU daily) based on age, AMH, BMI and prior response. Injections are subcutaneous, usually in the abdomen. Continued for 10–12 days.

2. LH — the supporter

Some protocols add LH (luteinising hormone) or HMG (mixed FSH+LH) to support follicular development, especially in women with low endogenous LH or poor response to FSH alone. Brand names: Menopur, Pergoveris, Luveris. Indications: older age, low AMH, prior poor response to pure FSH.

3. GnRH antagonist, preventing premature ovulation

GnRH antagonists block the LH surge that would trigger premature ovulation before retrieval. Brand names: Cetrotide, Orgalutran, Fyremadel. Started day 5–7 of stimulation when lead follicle reaches 14 mm. Continued until trigger. Subcutaneous daily injection.

4. GnRH agonist (long protocol)

Alternative to antagonist: GnRH agonist (Lupride, Buserelin) given pre-cycle to suppress the pituitary, then continued through stimulation. Used in long agonist protocol (especially for endometriosis). Initial flare of FSH/LH followed by suppression. Subcutaneous injection.

5. Trigger injection, final maturation

Triggers complete oocyte maturation ~36 hours before retrieval. Options: hCG (Ovitrelle, Pregnyl) — standard but higher OHSS risk; GnRH agonist trigger (Lupride single dose) — for OHSS-prone patients, paired with freeze-all; dual trigger, combination, used in selected cases. Subcutaneous or intramuscular.

6. Progesterone, luteal support

Maintains the endometrium after retrieval. Forms: vaginal pessaries (Crinone, Endometrin, Susten), intramuscular oil (P4 injections), oral (Duphaston, Susten oral). Started day of retrieval or transfer, continued until pregnancy test and through first trimester if positive. Each form has trade-offs in absorption and comfort.

7. Oestrogen, endometrial preparation

Used in frozen embryo transfer cycles to thicken the endometrium. Forms: oral oestradiol valerate, transdermal patches, vaginal preparations. Doses titrated by ultrasound monitoring. Continued through transfer and early pregnancy.

8. Side effects and what is normal

Bloating, mood swings, fatigue, mild headaches, injection site bruising, all expected. Severe abdominal distension, rapid weight gain, breathing difficulty, severe pain, call the clinic (possible OHSS). Allergic reactions to medications are rare but possible. Always keep emergency contact numbers visible.

Frequently Asked Questions