OHSS: Causes, Symptoms, and Treatment

This article is for general information only and is not a substitute for professional medical advice, diagnosis, or treatment. Always speak with your fertility specialist about symptoms during your own treatment cycle.

Quick takeaways

• OHSS (Ovarian Hyperstimulation Syndrome) is a known side effect of the fertility medications used to stimulate egg production during IVF.
• Most cases are mild and resolve on their own within one to two weeks.
• Risk is higher with PCOS, high AMH/follicle counts, and hCG-trigger cycles — but it's also one of the more preventable IVF complications when caught early.
• Severe OHSS is rare but needs urgent medical attention — know the red-flag symptoms below.

What Is OHSS?

Ovarian Hyperstimulation Syndrome happens when the ovaries react too strongly to the hormone injections used to grow multiple eggs for IVF. The ovaries swell, and fluid can shift from the bloodstream into the abdomen (occasionally the chest). According to ASRM's patient education fact sheet, roughly one in three people develop mild symptoms during stimulation, while moderate-to-severe OHSS is far less common.

OHSS is also classified by timing: "early" OHSS appears within about 9 days of the trigger injection; "late" OHSS shows up 10+ days afterward, often once pregnancy is confirmed.

What Causes OHSS?

OHSS is triggered by the hormone (usually hCG) used to mature the eggs before retrieval, layered on top of an already strong ovarian response to stimulation. A few factors raise that risk:

• Polycystic ovary syndrome (PCOS)
• High anti-Müllerian hormone (AMH) or a high antral follicle count, both markers of strong ovarian reserve
• A large number of follicles or eggs retrieved in the current cycle
• High estradiol levels during stimulation
• Pregnancy in the same cycle (a developing pregnancy produces its own hCG, which can prolong or worsen symptoms)

Clinics now screen for these markers before stimulation even begins, which is why your pre-cycle bloodwork and ultrasound count for more than just timing.

Symptoms by Severity

Mild symptoms are common and expected for many patients after stimulation — they're not a sign anything has gone wrong. Moderate and severe symptoms are where monitoring (and sometimes treatment) becomes necessary.

How OHSS Is Treated?

Treatment is matched to severity:

• Mild OHSS is usually managed at home with rest, hydration, and monitoring of weight and symptoms — most cases resolve on their own as hormone levels fall.
• Moderate OHSS typically calls for closer follow-up: more frequent ultrasounds and bloodwork to track fluid shifts and electrolyte levels, with outpatient symptom management.
• Severe OHSS can require hospitalization for IV fluids, electrolyte correction, and drainage of excess abdominal fluid (paracentesis) if breathing or comfort is affected. Because OHSS raises clotting risk, blood thinners are sometimes added. RCOG's Green-top Guideline outlines this staged approach.

Most patients recover within 10–14 days as the body reabsorbs the shifted fluid, though resolution can take longer if pregnancy occurs in the same cycle.

Prevention Matters More Than Treatment

Because OHSS is largely preventable, prevention matters more than treatment. Current ASRM guidelines favor GnRH-antagonist stimulation protocols, individualizing gonadotropin doses to ovarian reserve, and — for higher-risk patients — triggering with a GnRH agonist instead of hCG, or freezing all embryos for transfer in a later cycle. This is also why your choice of clinic matters: look for one that screens your AMH and follicle count up front and has a clear monitoring plan if your ovaries respond strongly. At Mannat Fertility Clinic, this kind of pre-cycle screening and individualized stimulation planning is standard for every IVF patient.

When to Seek Care Right Away?

Contact your fertility clinic immediately — or go to an emergency room if your clinic is unreachable — if you experience:

• Severe or worsening abdominal pain
• Weight gain of more than 2 lbs (about 1 kg) per day
• Significant shortness of breath
• Little to no urination for 24 hours
• Persistent vomiting or inability to keep fluids down
• Calf pain, swelling, or sudden dizziness (possible blood clot signs)

Don't wait out severe symptoms — early treatment prevents complications.

Why Choose Mannat Fertility?

With 15+ years of experience and over 23,000 families helped, Mannat Fertility is recognized as one of the best fertility clinics in Bangalore for personalized, closely monitored IVF care. Our specialists, led by Medical Director Dr. Archana Agarwal, build your stimulation protocol around your individual hormone profile — including your OHSS risk — from your very first consultation. If you're planning an IVF cycle, book an appointment with our team in Marathahalli or Whitefield to discuss a treatment plan suited to you.