Follitropin Alfa (Gonal-F) Side Effects: What to Expect and When to Call Your Doctor

Starting injections of follitropin alfa (Gonal-F) can feel overwhelming, especially when you're managing fertility treatment alongside everything else in your life. Understanding what side effects to expect — and crucially, which ones require urgent medical attention — will help you feel more in control throughout your treatment.

This guide covers both the everyday side effects most patients experience and the serious complications that require immediate medical attention.

Common Side Effects of Follitropin Alfa (Gonal-F)

Most patients tolerate Gonal-F well. The most commonly reported side effects include:

Headache — one of the most frequently reported side effects; usually mild to moderate

Nausea — typically mild, similar to early pregnancy nausea

Abdominal pain or bloating — a feeling of pressure or fullness in the lower abdomen as follicles grow; usually mild to moderate

Injection site reactions — redness, bruising, soreness, or itching at the injection site; rotating injection sites helps minimize this

Pelvic pain or discomfort — mild pelvic pressure is normal as your ovaries are being stimulated

Breast tenderness

Mood changes — some patients report emotional sensitivity during stimulation, likely related to hormonal changes

Serious Side Effects — Call Your Doctor Immediately

The following side effects are less common but require urgent medical attention. Do not wait for your next scheduled appointment if you experience these:

Ovarian Hyperstimulation Syndrome (OHSS)

OHSS is the most important serious complication of Gonal-F therapy. It occurs when the ovaries respond too strongly to FSH stimulation, leading to dramatically enlarged ovaries and fluid leaking from blood vessels into the abdomen and chest. OHSS can range from mild to life-threatening.

Warning signs of OHSS — call your doctor or go to the ER if you experience:

Severe pelvic pain (not mild bloating — significant pain)

Rapid weight gain (more than 1–2 lbs per day due to fluid accumulation)

Severe nausea or vomiting

Abdominal distension (visibly swollen abdomen)

Shortness of breath or difficulty breathing

Decreased urination

Ovarian Torsion

Enlarged ovaries during stimulation can sometimes twist on their blood supply — a surgical emergency called ovarian torsion. Symptoms include sudden, severe one-sided pelvic pain, often accompanied by nausea and vomiting. If you experience this, go to the emergency room immediately.

Allergic Reactions

Rare but serious allergic reactions including anaphylaxis have been reported with Gonal-F use. Symptoms may include facial swelling, difficulty breathing, severe rash, or hives. If you experience these symptoms after an injection, call 911 immediately.

Blood Clots (Thromboembolic Events)

Both OHSS and pregnancy increase the risk of blood clots. If you experience sudden leg pain, swelling in one leg, chest pain, or shortness of breath, seek emergency care immediately.

Multiple Gestation

Gonal-F stimulates multiple follicles, raising the risk of conceiving twins, triplets, or more. Multiple gestation carries significant risks for both mother and babies, including preterm birth and low birth weight. Your doctor will monitor follicular development closely and may withhold the hCG trigger shot if too many follicles develop.

How to Reduce Side Effect Risk

Follow your dosing instructions exactly — never take more than prescribed

Attend all monitoring appointments (blood tests and ultrasounds)

Stay well hydrated — drink at least 8–10 glasses of water per day during stimulation

Avoid strenuous exercise during stimulation (enlarged ovaries are more vulnerable to torsion with vigorous activity)

Report any new or worsening symptoms to your clinic promptly — don't wait to see if they improve on their own

For information on drug interactions with Gonal-F, read our Gonal-F drug interactions guide. And if you're having trouble filling your Gonal-F prescription, medfinder can help you locate it at pharmacies near you.