Fertility Medications: What You Need to Know

The first time you see your fertility medication protocol, it can be overwhelming. A list of drug names you have never heard of, dosages in unfamiliar units, injection schedules that seem complicated, and warnings about side effects that sound alarming. You might wonder how you will keep it all straight, or whether these hormones will change how you feel.

These concerns are completely normal. Fertility medications are powerful tools, and understanding what you are putting into your body matters. You deserve to know not just what to take and when, but why each medication is used, how it works, and what to realistically expect in terms of side effects.

This guide breaks down the most common fertility medications in plain language. Consider it your reference as you navigate treatment, something you can return to when you need a reminder of what a particular medication does or why it is part of your protocol.

Understanding How Fertility Medications Work

To make sense of individual medications, it helps to understand the basics of what they are trying to accomplish.

The Natural Hormonal Cycle

In a natural menstrual cycle:

1. Your brain releases FSH (follicle-stimulating hormone), signalling the ovaries to develop follicles
2. Follicles grow and produce estrogen
3. When estrogen reaches a certain level, your brain releases LH (luteinizing hormone), triggering ovulation
4. After ovulation, the empty follicle produces progesterone to prepare the uterine lining for implantation

Fertility medications work by enhancing, modifying, or controlling various parts of this cycle.

Goals of Fertility Medications

Depending on your treatment, medications might be used to:

• Induce ovulation in women who do not ovulate regularly
• Stimulate multiple follicles to develop (for IVF)
• Control timing of ovulation for procedures like IUI
• Prevent premature ovulation during IVF stimulation
• Support the uterine lining after transfer
• Address specific hormonal imbalances

For detailed information on the treatments these medications support, see our fertility treatments hub.

Medications for Ovulation Induction

These medications help women who do not ovulate regularly (often due to PCOS or other hormonal conditions).

Letrozole (Femara)

What it is: An aromatase inhibitor, originally developed for breast cancer treatment but now widely used for ovulation induction.

How it works: Letrozole temporarily blocks estrogen production. Your brain interprets this as low estrogen and responds by releasing more FSH, which stimulates follicle development.

How it is taken: Oral tablets, typically 2.5-7.5mg daily for 5 days, starting on cycle day 2-5.

Common side effects:

• Hot flashes
• Headache
• Fatigue
• Breast tenderness

Why it is often preferred: Letrozole has become the first-line medication for PCOS-related infertility because studies show higher pregnancy rates compared to Clomid. It also has a lower risk of multiple pregnancy.

Clomid (Clomiphene Citrate)

What it is: A selective estrogen receptor modulator (SERM), the traditional first-line ovulation induction medication.

How it works: Clomid blocks estrogen receptors in the brain, tricking your body into thinking estrogen is low. This triggers increased FSH release and follicle development.

How it is taken: Oral tablets, typically 50-150mg daily for 5 days, starting on cycle day 2-5.

Common side effects:

• Hot flashes
• Mood changes
• Headache
• Bloating
• Visual disturbances (rare, but should be reported immediately)
• Cervical mucus changes (can become hostile to sperm)
• Thinning of uterine lining (with prolonged use)

Limitations: The anti-estrogenic effects on cervical mucus and uterine lining can sometimes counteract the benefits of ovulation induction.

Metformin (Glucophage)

What it is: A diabetes medication that improves insulin sensitivity.

How it works: Many women with PCOS have insulin resistance, which contributes to hormonal imbalances and anovulation. By improving insulin sensitivity, metformin can help restore normal ovulation.

How it is taken: Oral tablets, typically 500-2000mg daily, often in divided doses.

Common side effects:

• Gastrointestinal issues (nausea, diarrhea, stomach upset), especially when starting
• Metallic taste
• Vitamin B12 deficiency with long-term use

Tips for tolerating it: Start with a low dose and increase gradually. Take with food. Extended-release formulations cause fewer GI side effects.

Role in fertility: Usually used alongside Letrozole or Clomid rather than alone, particularly in women with significant insulin resistance.

Injectable Gonadotropins

These are the medications used for IVF stimulation and sometimes for more intensive ovulation induction when oral medications have not worked.

FSH Medications (Follicle-Stimulating Hormone)

Brand names: Gonal-F, Follistim, Puregon, Bemfola

What they are: Synthetic or highly purified versions of FSH, the hormone your brain naturally produces to stimulate follicle development.

How they work: By injecting FSH directly, you bypass the brain's control and stimulate the ovaries to develop multiple follicles rather than just one.

How they are taken: Subcutaneous injection (under the skin, usually in the abdomen), daily during stimulation.

Common side effects:

• Injection site reactions (redness, bruising)
• Bloating and abdominal discomfort as follicles grow
• Mood changes
• Headache
• Ovarian hyperstimulation syndrome (OHSS) in more severe cases

LH-Containing Medications

Brand name: Menopur

What it is: Contains both FSH and LH (luteinizing hormone).

Why LH is sometimes added: Some women benefit from LH supplementation during stimulation, particularly those with very low baseline LH or certain protocols.

How it is taken: Similar to FSH-only medications, daily subcutaneous injection.

hMG (Human Menopausal Gonadotropin)

What it is: An older formulation derived from the urine of postmenopausal women, containing both FSH and LH.

Current use: Largely replaced by recombinant (synthetic) products in many clinics, though still available and effective.

Medications to Control Ovulation Timing

During IVF, it is crucial to prevent premature ovulation before egg retrieval. These medications provide that control.

GnRH Agonists

Brand names: Lupron (leuprolide), Buserelin, Synarel (nasal spray)

How they work: Initially, GnRH agonists cause a surge of FSH and LH (the "flare"). With continued use, they suppress your brain's production of these hormones, preventing a natural LH surge and premature ovulation.

Common protocols:

• "Long protocol": Started before stimulation to fully suppress the system
• "Flare protocol": Started with stimulation to use the initial surge for extra stimulation

Side effects:

• Hot flashes
• Headache
• Mood changes
• Vaginal dryness

GnRH Antagonists

Brand names: Cetrotide, Ganirelix (Orgalutran)

How they work: Antagonists block GnRH receptors immediately, quickly preventing LH surge without the initial flare. They work within hours.

When they are used: Typically started mid-stimulation (around day 5-6) when follicles reach a certain size, continuing until trigger.

Advantages:

• Shorter duration of use
• Fewer side effects
• Lower OHSS risk
• Simpler protocol

Side effects:

• Injection site reactions
• Headache
• Nausea

Trigger Medications

These medications cause final egg maturation and trigger ovulation at a precise time, allowing scheduled egg retrieval or timed IUI.

hCG (Human Chorionic Gonadotropin)

Brand names: Ovidrel, Pregnyl, Novarel

What it is: A hormone structurally similar to LH, causing the same effect of triggering ovulation.

How it works: Injection triggers final egg maturation and ovulation approximately 36-40 hours later.

How it is taken: Single intramuscular or subcutaneous injection when follicles are mature.

Considerations: hCG can worsen OHSS risk in high-responders because it stimulates the ovaries for longer than natural LH.

GnRH Agonist Trigger (Lupron Trigger)

What it is: Using a GnRH agonist (like Lupron) instead of hCG to trigger ovulation.

How it works: The agonist causes your brain to release a natural LH surge.

Why it is used: Significantly reduces OHSS risk, making it preferred for high-responders and freeze-all cycles.

Limitations: Sometimes results in lower progesterone support, requiring more aggressive supplementation. May have slightly lower success in fresh transfers (less of an issue in freeze-all cycles).

Progesterone Support

After ovulation or egg retrieval, progesterone prepares and maintains the uterine lining for implantation.

Why Supplementation Is Needed

During IVF, the normal feedback systems are disrupted. The corpus luteum (which naturally produces progesterone) may not function optimally, especially after egg retrieval removes follicular cells. Supplementation ensures adequate progesterone levels.

Forms of Progesterone

Vaginal suppositories or gel:

• Brand names: Crinone, Endometrin, Utrogestan
• Delivered directly to the uterus
• Common side effects: vaginal irritation, discharge

Intramuscular injections:

• Brand name: Progesterone in oil
• Higher blood levels, sometimes preferred
• Side effects: painful injection site, oil may be thick

Oral progesterone:

• Less commonly used because absorption is less reliable
• May be used as supplementation

Duration of Use

Progesterone is typically continued until 8-12 weeks of pregnancy, when the placenta takes over hormone production. If the cycle is not successful, progesterone is stopped, and a period will follow.

Other Supporting Medications

Estrogen

Forms: Patches (Estraderm, Climara), oral tablets (Estrace, Progynova), vaginal tablets

When used: In frozen embryo transfer cycles to build the uterine lining, and sometimes to support fresh cycles.

Side effects: Breast tenderness, bloating, mood changes, headache

Dexamethasone or Prednisone

What they are: Corticosteroids (steroids)

When used: Sometimes prescribed to reduce inflammation or suppress certain immune responses that might affect implantation. Also used in some PCOS protocols to reduce androgen levels.

Baby Aspirin (Low-Dose Aspirin)

When used: Some protocols include low-dose aspirin to improve blood flow to the uterus. Evidence is mixed, but it is low-risk.

Thyroid Medication

When used: If thyroid levels are suboptimal, levothyroxine may be prescribed. Proper thyroid function is important for fertility and early pregnancy.

Managing Side Effects

Fertility medications are powerful, and side effects are common. Here is how to cope.

Physical Side Effects

Bloating and discomfort: Your ovaries are growing larger than normal. Wear loose clothing, stay hydrated, and avoid strenuous exercise.

Injection site issues: Rotate injection sites, ice the area beforehand if needed, and ensure proper technique.

Hot flashes: Dress in layers, keep rooms cool, and know they are temporary.

Headaches: Stay hydrated, and ask your doctor about safe pain relievers.

Emotional Side Effects

Hormone fluctuations can affect mood. You might feel:

• Irritable
• Anxious
• Emotional or weepy
• Like you are "not yourself"

These feelings are real and valid. Communicate with your partner about what you are experiencing. Consider support from a counsellor who understands fertility treatment.

When to Call Your Doctor

Contact your clinic if you experience:

• Severe abdominal pain
• Difficulty breathing
• Significant weight gain (more than 2kg in a day)
• Decreased urination
• Visual disturbances
• Signs of infection at injection sites

Key Takeaways

• Ovulation induction medications (Letrozole, Clomid) help women who do not ovulate regularly. Letrozole is often preferred for PCOS.

• Injectable gonadotropins (Gonal-F, Follistim, Menopur) directly stimulate the ovaries and are the cornerstone of IVF stimulation.

• GnRH antagonists (Cetrotide, Ganirelix) prevent premature ovulation during IVF.

• Trigger medications (hCG or Lupron) time ovulation precisely for procedures.

• Progesterone supports the uterine lining after ovulation or transfer and is typically continued into early pregnancy.

• Side effects are common but manageable. Communicate with your medical team about what you are experiencing.

This content is for educational purposes only and should not replace professional medical advice. Always follow your clinic's specific instructions for your medications. Do not adjust dosages without consulting your medical team.

Last updated: January 2026