If you are on fertility treatments and have been prescribed Clomid or HCG, it is essential for you to know the differences between these medications. 

When deciding which one of these drugs to take, you should know about their mechanisms of action and side effects. Many infertile women who face difficulty in getting pregnant, mostly have a hormone imbalance. 

Clomid(Clomiphene/Clomifene) and HCG(Human Chorionic Gonadotropin) will either raise the levels of Gonadotropins; the FSH and LH, in your body, which helps to stimulate more ovarian follicles to form during ovulation, or it can help with maturation of follicles.

In this article, we will discuss how Clomid and HCG work so that you can make an informed decision!

1. What is Clomid, and how does it work

Clomid is a synthetic drug that contains Clomifene, used for infertility treatment. Clomifene appears to stimulate the release of gonadotropins; follicle-stimulating hormone (FSH), and luteinizing hormone (LH), which leads to the development and maturation of the ovarian follicles, ovulation, and subsequent development and function of the corpus luteum, thus resulting in pregnancy. 

pregnant woman

It increases the production of Gonadotropins from the pituitary gland. It does so by competing for estrogenic receptors located in the uterus, pituitary gland, and hypothalamus, leading to decreased binding of estrogen with its receptors and decreased negative feedback to the pituitary-hypothalamic axis (tricking the body that Gonadotropins are not being produced in sufficient quantity to occupy receptors). That eventually leads to increased production of FSH and LH by the pituitary gland. 

However, as this (pituitary-hypothalamic axis) pathway involves the hypothalamus, it’s important to note that it only works for women with intact hypothalamic function. For those with a damaged hypothalamus, Clomid will not work.

2. What are the side effects of Clomid

There are some side effects associated with Clomid. Side effects vary from woman to woman and range from mild to very severe. 

For this reason, it is essential that you inform your doctor if you experience any symptoms while taking Clomid so that they can determine what course of action to take next, before it’s too late. 

The most common untoward effects might include:

  • Headache
  • Dizziness
  • Bloating
  • Stomach disorders
  • Abdominal fullness
  • Breast tenderness
  • Mood swings (feeling moody or irritable)
  • Hot flashes (sudden feeling of heat and sometimes a red flushed face and sweating)

The use of Clomifene can lead to some serious untoward effects as listed below:

  • Vision Problems (blurred vision, seeing spots or flashes especially when exposed to bright light)
  • OHSS (Ovarian hyperstimulation syndrome): It's a very rare but serious syndrome that leads to fluid accumulation in the stomach, chest, and heart area. If you feel rapid weight gain, shortness of breath, nausea, diarrhea, palpitations, you should consult your doctor immediately. {1}
  • Vaginal bleeding

3. What is HCG, and how does it work

On the other hand, HCG is a hormone that comes from the placenta of pregnant women. It triggers the final follicular maturation and ovulation and also helps in the luteal phase of the ovarian cycle. {2} 

HCG can be used as a fertility drug, and it's also used for weight loss programs. HCG can be injected under your skin into your muscle tissue, to be absorbed into the bloodstream because it can't be absorbed through the Gastrointestinal tract, which might also lead to unpleasant side effects such as nausea and vomiting. 

4. What are the side effects of HCG

Many patients who take HCG treatment might experience:

  • Pain at the injection site
  • Headaches
  • Restlessness
  • Irritability
  • Some people also report feeling sick to their stomachs or having diarrhea.
Woman with a headache

These side effects usually only last for the first few days while taking HCG but consult your doctor if they persist even after completion of treatment or become troublesome. HCG is a bit more potent than Clomid, so it’s essential to start with a low dose and increase gradually as needed. 

Unlike Clomid, there is no evidence that HCG can cause ovarian hyperstimulation syndrome (OHSS), but it’s still important to monitor your baseline reports while taking HCG just in case.

5. Comparing Clomid and HCG

Both Clomid and HCG are injected into the body to trigger ovulation, but their development and usage differ. The main difference is that Clomid is a non-steroidal medication while HCG belongs to steroids. 

This means that it has no side effects for women who do not have fertility issues and those with PCOS or other health conditions associated with steroid use, such as blood clotting disorders. 

Clomid is used more as a diagnostic tool to determine if there is an ovulatory dysfunction and not as frequently as HCG for ovulation induction. 

Clomid alone is considered to be ineffective for inducing ovulation in women facing infertility, because of hyperprolactinemic amenorrhea. However, when the Clomid treatment is combined with the HCG treatment there is a remarkable improvement regarding ovulation in infertile women. In a study when HCG treatment was combined with the Clomid treatment, the ovulation rate increased to 90%, and the pregnancy rate was reported to be up to 57%. {3} 

6. Which drug is right for you?

This is a question that only your doctor can answer. Some factors that will be considered include the cause of infertility, your age, and how long you have been trying to conceive.

Clomid is often prescribed for women who are not ovulating due to an imbalance of hormones. HCG is used to treat fertility problems in men also. 

It stimulates the production of testosterone and leads to increased production of sperms. If you have been trying to conceive for more than six months, your doctor may recommend you to use HCG in addition to Clomid. 

7.  Make an informed decision!

When choosing between FSH drugs, you should consider your personal preferences and needs. For example, some women prefer injectable hormones to avoid swallowing pills. On the other hand, many patients report severe injection site pain while using HCGs. 


If you cannot tolerate frequent needle pricks or if you have a phobia of needles, oral medications such as Clomid might be a better choice for you! 

However, it is best to always consult with the qualified professionals before making any health decisions to ensure that these treatments are suitable for your body or not.

Frequently Asked Questions

Q. What is the best time to take Clomid?

  1. If you are trying to get pregnant, you may be wondering when is the best time to take Clomid. The answer depends on your situation. Most doctors recommend taking Clomid starting on the 3rd, 4th, or 5th  day of your menstrual/ovarian cycle and continuing for up to five days. {4} However, if you take Clomid for other reasons, such as to induce ovulation after a miscarriage or medical condition      that affected your menstrual cycle, you may need to take the medication longer.

Q. How long does it take for HCG to work?

  1. After receiving an injection of HCG, it takes 24 to 48 hours, averaging up to 36 hours for eggs to ovulate and be in prime condition to be fertilized.

Q. How long does it take Clomid to work?

  1. Clomid starts a chain reaction (that will eventually lead to ovulation) when you take it’s first dose, and the ovulation occurs usually after 5 days of the last pill.


Now that you know the difference between Clomid and HCG, what route do you plan to take? 

First, Before starting any treatment, seek medical advice from a qualified medical professional. And then, after getting briefed about all the available options, you should make a decision to select a treatment plan. 

Some people get pregnant on their first round of Clomid, while others may need a few more rounds before they conceive. 

The same thing goes for HCG; some women get results right away, whereas others take several weeks or months. 

Also, keep in mind that you may need to combine the two treatments for the best results. Your doctor will determine the best steps after examining all factors such as age, weight, etc.


1. "Ovarian Hyperstimulation Syndrome: Causes, Symptoms, and More." 9 Mar. 2021, https://www.webmd.com/infertility-and-reproduction/what-is-ovarian-hyperstimulation-syndrome. Accessed 28 Jan. 2022.

2.  "The Development of Gonadotropins for Clinical Use in the Treatment ...." 3 Jul. 2019, https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6616070/. Accessed 28 Jan. 2022.

3. "Induction of ovulation in women with hyperprolactinemic ... - PubMed." https://pubmed.ncbi.nlm.nih.gov/467699/. Accessed 28 Jan. 2022.

4. "Fertility Drug Types: Injectable Hormones, Clomid, and More." 8 Jun. 2021, https://www.webmd.com/infertility-and-reproduction/guide/fertility-drugs. Accessed 28 Jan. 2022.

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