Human chorionic gonadotropin (hCG) is sometimes called “the pregnancy hormone” because of its important role in maintaining pregnancy. Pregnancy tests check hCG levels in the urine or blood to determine if the test in positive or negative.

HCG injection is also approved by the U.S. Food and Drug Administration (FDA) to treat specific medical conditions in both women and men.

In women, hCG injections are FDA-approved to help treat infertility.

In men, hCG injections are FDA-approved for a type of hypogonadism in which the body doesn’t adequately stimulate the gonads to produce the sex hormone testosterone.

In men, doctors prescribe hCG to combat the symptoms of hypogonadism, such as low testosterone and infertility. It can help the body increase production of testosterone and increase sperm production, which can reduce infertility.

Injections of hCG are also sometimes used as an alternative to testosterone products in men with testosterone deficiency. Testosterone deficiency is defined as testosterone blood levels less than 300 nanograms per deciliter along with symptoms of low testosterone. These include:

According to the American Urological Association, hCG is appropriate for those men with testosterone deficiency who also desire to maintain fertility.

Testosterone products boost levels of the hormone in the body but can have the side effects of shrinking the gonads, altering sexual function, and causing infertility. HCG can help increase testosterone levels, increase fertility, and increase gonad size.

Some doctors think that using testosterone along with hCG might improve symptoms of testosterone deficiency while preventing some of the testosterone side effects.

There is also speculation that hCG might help improve sexual function in men who don’t have improvement while on testosterone.

Bodybuilders who take anabolic steroids such as testosterone also sometimes use hCG to prevent or reverse some of the side effects cause by steroids, such as gonad shrinkage and infertility.

In men, hCG acts like luteinizing hormone (LH). LH stimulates Leydig cells in the testicles, which results in the production of testosterone. LH also stimulates production of sperm within structures in the testicles called seminiferous tubules.

As hCG stimulates the testicles to produce testosterone and sperm, the testicles grow in size over time.

Very little clinical research has evaluated hCG in men with low testosterone levels. In a small study of men with hypogonadism, hCG increased testosterone levels compared to a placebo control. There was no effect of hCG on sexual function.

In one study, men taking testosterone along with hCG were able to maintain adequate sperm production. In another study, men taking testosterone along with hCG were able to maintain testosterone production in the testicles.

The most common side effects men experience when hCG injections are used include:

  • growth of male breasts (gynecomastia)
  • pain, redness, and swelling at the injection site
  • stomach pain
  • nausea
  • vomiting

In rare cases, people taking hCG have developed blood clots. Although also rare, allergic reactions can occur, including mild skin rashes and severe anaphylactic reactions.

HCG is sometimes used for weight loss. Several products are available that are marketed as over-the-counter homeopathic hCG products for weight loss.

However, the FDA has warned that there are no FDA-approved hCG products for this purpose. Over-the-counter products claiming to contain hCG aren’t legally authorized. The FDA has also advised that there is no substantial evidence that hCG works for weight loss.

These products are often used as part of the “hCG diet.” This typically involves taking hCG supplements while following a low-calorie diet of 500 calories per day. Although this low-calorie diet can reduce weight, there is no evidence that using hCG products helps. Additionally, this extremely low-calorie diet can be unsafe for some people.

When used appropriately with the guidance of your doctor, hCG is safe. It shouldn’t be used by men with prostate cancer, certain brain cancers, or uncontrolled thyroid disease. Talk with your doctor about your other medical conditions before using hCG.

HCG is produced from hamster ovary cells. People with an allergy to hamster protein shouldn’t take hCG.

There are no FDA-approved over-the-counter hCG products. The FDA warns against using these products or following the hCG diet. There is no evidence that hCG helps for weight loss, and the very low-calorie diet might be harmful.

Extremely restrictive diets can result in electrolyte imbalances and gallstone formation.

HCG is an FDA-approved medication for treating specific conditions in both women and men. In men, it seems to have an important role as an alternative to testosterone for boosting testosterone levels and maintaining fertility.

Some doctors are prescribing it in conjunction with testosterone products for testosterone deficiency to help maintain fertility and sexual function.

Some people are also using hCG for weight loss, often as a component of the hCG diet. However, there is no reliable evidence that hCG works for this purpose, and it might not be safe.