Ovarian Hyperstimulation Syndrome: Causes, Symptoms, and Treatment

Medically reviewed by Harsha Moole, MD, Internal Medicine. Last reviewed: October 23, 2026.

What kind of doctor treats Ovarian Hyperstimulation Syndrome?

A reproductive endocrinologist, a doctor who treats fertility problems, usually manages ovarian hyperstimulation syndrome (OHSS). This is often the doctor who gave the fertility medicines. An ob-gyn, a doctor for women's health, may also help. A direct primary care or concierge doctor can be a first stop for an evaluation and can refer you to a specialist when needed.

What is ovarian hyperstimulation syndrome?

OHSS is a problem seen in some women who take fertility medicines that make eggs grow. It is most common in people having in vitro fertilization (IVF), where eggs are fertilized outside the body. If the medicines stimulate the ovaries too much, the ovaries can become very swollen. Fluid can leak into the belly and chest area. OHSS happens only after the eggs are released from the ovary. It rarely happens in women who only take fertility medicines by mouth.

Symptoms

OHSS ranges from mild to severe. About one in three people have mild symptoms during IVF treatment. Mild symptoms include:

  • Belly bloating and mild pain in the belly.
  • Nausea and weight gain due to fluid.

Severe OHSS is less common. Signs can include fast weight gain (more than 10 pounds, or 4.5 kilograms, in 3 to 5 days), severe belly pain or swelling, less urine, shortness of breath, and blood clots. People with severe OHSS usually vomit and cannot keep liquids down. Symptoms usually start a few days after ovulation.

Causes and who gets it

OHSS is more likely if you get a shot of human chorionic gonadotropin (hCG), a hormone that triggers the release of eggs. It is also more likely if you get more than one dose of hCG after ovulation. Getting pregnant during the cycle raises the risk too. Other risk factors include:

  • Being younger than age 35.
  • Having a very high estrogen level during fertility treatment.
  • Developing an unusually large number of ovarian follicles, the small sacs in which eggs grow.
  • Having polycystic ovary syndrome (PCOS), low body weight, or large ovarian cysts.

How doctors diagnose it

Your doctor will ask about your fertility treatment and symptoms. Your weight and belly size will be measured. Tests may include an ultrasound of the belly or vagina, a chest x-ray, and blood tests. These check blood counts, minerals called electrolytes, and how well the liver works. Your doctor may also measure how much urine you make.

A standard pelvic exam is generally not recommended with OHSS. The ovaries are enlarged, and the cysts that are present may burst under pressure.

Treatment

Mild cases of OHSS usually do not need treatment. These steps can ease discomfort:

  • Rest with your legs raised. Light activity now and then is better than total bed rest, unless your provider says otherwise.
  • Drink plenty of fluids, especially drinks with electrolytes, and avoid alcohol and caffeinated drinks.
  • Avoid intense exercise and sexual intercourse, which may cause cysts to rupture or the ovaries to twist and cut off blood flow.
  • Take an over-the-counter pain reliever such as acetaminophen (Tylenol), if your provider agrees.
  • Weigh yourself each day. Gaining 2 or more pounds (about 1 kilogram) a day is too much.

Doctors also advise doing less and drinking lots of fluids with electrolytes. Medicines for nausea are available. If fluid builds up in the belly, draining it with a needle (paracentesis) can bring relief in most cases. Severe OHSS may need care in the hospital. There you may get fluids through a vein, and fluid that has collected in the body may be removed. If severe OHSS is found before an IVF embryo transfer, the embryos may be frozen and transferred later.

When to see a doctor

Contact your provider if you have less urine, dizziness, fast weight gain, or very bad nausea. Very bad nausea means you cannot keep food or liquids down. Blood clots can form in the legs. They can travel to the lungs, which can be life threatening. Call 911 or go to the emergency room if you have trouble breathing, chest pain, fainting, severe or sudden belly pain, or leg swelling or redness.

How a direct primary care or concierge doctor fits in

A direct primary care doctor charges a flat monthly fee instead of billing insurance, while a concierge doctor usually charges more and often works alongside insurance. Such a doctor can help you spot warning signs early, check in on your symptoms, and coordinate with your fertility clinic.

Common questions

How long does ovarian hyperstimulation syndrome last?

Most mild cases go away on their own after your period starts. Symptoms usually go away within two weeks unless pregnancy occurs. Severe cases can take several days to improve.

Is OHSS dangerous?

It can be, but most cases are mild. In rare cases, OHSS can cause blood clots, kidney failure, or a serious mineral imbalance. Fluid can also build up in the belly or chest. Careful monitoring is important.

Can doctors prevent OHSS?

Doctors can lower the risk in several ways. If you get fertility injections, you will have regular blood tests and pelvic ultrasounds to check that your ovaries are not over-responding. Lower doses of stimulation medicines may reduce the risk.

Does pregnancy make OHSS worse?

It can. If you become pregnant during OHSS, symptoms may get worse and can take weeks to go away. Freezing eggs or embryos for later transfer can help OHSS get better more quickly.

Sources

  1. MedlinePlus - Ovarian hyperstimulation syndrome
  2. American Society for Reproductive Medicine - Ovarian Hyperstimulation Syndrome (OHSS)

Medical Disclaimer

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