Ovarian Hyperstimulation Syndrome (OHSS): Causes, Symptoms and Treatment

For many couples struggling to conceive, fertility drugs are the first step in the journey to getting pregnant. However, if some cases, they can trigger a very unwanted side effect: Ovarian Hyperstimulation Syndrome (OHSS). If you’re undergoing fertility treatment, it’s important to know the signs so you can get the treatment you need.

Ovarian Hyperstimulation Syndrome (OHSS): What is it?

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Fertility drugs work by triggering the ovulation. However, if they overdo it, this can sometimes over-stimulate the ovaries, causing them to become swollen. In most cases, this is relatively mild, but can cause fluid build-up. In more serious instances, however, it can lead to severe abdominal pain, fluid collection in the abdomen and chest. Rarely, this may require hospitalization due to the risk of thrombosis, renal failure and respiratory failure.

What Causes Ovarian Hyperstimulation Syndrome (OHSS)?


In many cases, OHSS is triggered by fertility drugs used by couples undergoing assisted reproduction treatments. These medications work by stimulating the ovarian follicles into developing enough to release an egg. However, in OHSS, sometimes too many of these follicles start maturing all at once, swelling the ovary from its usual size of around 5 cm to around 10 cm. In a natural ovulation cycle, only one of these follicles will grow to its full size.

The following risk factors are thought to increase the odds of developing OHSS.

  • Low body weight
  • Younger age (between 18 to 35)
  • Polycystic Ovary Syndrome (PCOS), a condition that interferes with the number of ovarian follicles that develop for ovulation.

OHSS generally occurs as a side of effect of fertility treatment, and OHSS is more common in patients taking fertility treatment with injectable gonadotropins.

Ovarian Hyperstimulation Syndrome (OHSS) Symptoms

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If you’re taking fertility drugs and experience any of the following symptoms, talk to your doctor about OHSS right away.

Fluid build-up in the abdomen

Fluid can begin to collect in the abdomen as the ovaries become enlarged. This can result in an uncomfortable feeling of fullness or tightness in the lower belly. You may also notice this as increased body weight, even if your eating habits haven’t changed, so stay on the look-out for any sudden weight gain.


Fluid build-up in the abdomen can increase pressure on the surrounding organs, causing pain, nausea and even vomiting. Be sure not to overlook any queasiness.

Symptoms of dehydration

In severe cases, OHSS can result in dehydration, which you may notice as symptoms like a persistently dry throat or decreased volume of urination. This could be a sign your body doesn’t have the fluids it needs, so get to a doctor right away.

What is the treatment for OHSS?

OHSS is usually very mild, so the only treatment required is watchful waiting from your healthcare provider while you undergo fertility treatment.

However, when OHSS is severe, symptoms like abdominal pain and feeling of tightness in the belly can be signs of fluid build-up in the abdomen, and in rare cases, this may require hospitalization. In this case, the woman is usually treated by stopping the fertility therapy, draining excess fluid from the belly, addressing a risk of blood clots, and restoring lost fluids.

If you notice any of the symptoms of OHSS, speak to your fertility specialist. There may be another ovulation-stimulating treatment that better suits you.

Can I get pregnant if I have OHSS?


It’s still possible to get pregnant if you develop OHSS. However, pregnancy throws your hormones for a loop, which may make OHSS last longer or worsen your symptoms. On top of that, if you fall pregnant while ovulating a larger than normal number of eggs, you have an increased odds of twins or multiple births, putting even more strain on your body. For this reason, your fertility specialist may offer the option of stopping fertility treatment and focusing on treating OHSS at first before getting pregnant.

Watch for OHSS symptoms during fertility treatment

Ovarian Hyperstimulation Syndrome is usually mild, but left untreated, the consequences can be severe – even life-threatening. However, if you stay on the look-out for symptoms, you’ll know when to go to a doctor. Early diagnosis and treatment can reduce your risk of complications, so don’t hesitate to see a doctor if you’re concerned about OHSS.