Updated by the Progyny Clinical Team — August 2025.
What is Clomid?
Clomid (clomiphene citrate) is one of the most common medications used in fertility treatment. It’s what’s called a selective estrogen receptor modulator (SERM). That means it attaches to the same receptors that estrogen normally does, but it changes how your body receives the signal.
Clomid works by adjusting the usual communication between your ovaries and your brain. Normally, your brain releases a hormone called follicle-stimulating hormone (FSH). FSH helps a follicle — the small fluid-filled sac that carries an egg — grow on your ovary. As the follicle grows, it releases estrogen. Rising estrogen tells your brain to lower FSH, so usually only one follicle grows each month.
When you take Clomid, it blocks the estrogen receptors in your brain. Because of this, your brain “thinks” your estrogen levels are low and continues to release more FSH. That extra FSH can help your ovary grow a follicle — or sometimes more than one. Having multiple follicles may increase your chance of pregnancy, though it also comes with some risks.
The risk of multiple pregnancy
One possible side effect of Clomid is a multiple pregnancy (twins or more). In some cases, your fertility specialist may want more than one follicle to grow, because this can raise your chance of success. But it’s always a balance between improving your odds and reducing risk. If you get pregnant using Clomid with timed intercourse or an intrauterine insemination, the chance of a multiple pregnancy is about 7% to 10%. It depends on your age and how many follicles develop.
Other possible side effects
Clomid is generally well tolerated. It works quickly and leaves your system fast — it’s usually taken for just five days during a cycle. Many people have no side effects at all, while others notice mild symptoms that end once treatment is finished.
The most common effects are mood swings, which affect more than 50% of people, and hot flashes, which happen in about 20%. A smaller number report breast tenderness, nausea, pelvic pressure, or headaches. These symptoms are usually mild and temporary.
Less commonly, Clomid may cause vision changes, such as blurred or double vision, light sensitivity, or small blind spots. This happens in only 1% to 2% of people and usually goes away once the medication is stopped. Because rare cases of lasting vision symptoms have been reported, it’s important to tell your fertility doctor right away if this happens to you. In most cases, your doctor will stop the medication.
Since Clomid sometimes stimulates more than one follicle, you may also feel abdominal bloating or pelvic pressure during treatment, depending on how your ovaries respond.
Key takeaways
- Clomid is a common fertility medication that helps stimulate ovulation by blocking estrogen signals in the brain.
- Most people have no side effects or only mild ones, and symptoms usually go away quickly.
- Common side effects include mood swings, hot flashes, and nausea.
- Rare but more serious side effects, such as vision changes or severe pain, should be reported to your doctor immediately.
If you have questions or concerns, Progyny is here for you. Please contact your Progyny Care Advocate for support.
Disclaimer: The information provided by Progyny is for educational purposes only and is not medical advice. Always consult a qualified healthcare provider for medical guidance.