Clomid (Clomiphene Citrate)

Clomid is a selective estrogen receptor modulator prescribed at 50 mg daily for 5 days to induce ovulation in women with irregular cycles, and used off-label in men to raise testosterone while preserving fertility.

• Dose range: 50 mg once daily for 5 days per cycle; up to 100 mg for resistant cases
• Prescription status: Clomid is Rx only in the United States
• Primary warning: Stop Clomid and call your doctor if vision changes start
• Half-life: 5 days (zuclomiphene), traces linger up to 6 weeks

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What Is Clomid?

Clomid is the brand name for clomiphene citrate. The FDA approved clomiphene in 1967. Clomiphene belongs to a class called selective estrogen receptor modulators, or SERMs. Clomid comes as a 50 mg oral tablet. A second brand, Serophene, contains the same active ingredient.

Clomiphene citrate is a white to pale yellow crystalline powder. It is freely soluble in methanol. Oral bioavailability is high. Peak serum concentration occurs within 4 to 6 hours. Clomid is metabolized in the liver. It is excreted primarily through feces. The half-life varies by isomer. Zuclomiphene clears in 5 days. Enclomiphene clears in 10 days per FDA pharmacokinetic data.

How Clomid Works in the Body

Clomid blocks estrogen receptors in the hypothalamus. The hypothalamus normally senses circulating estrogen and suppresses gonadotropin-releasing hormone secretion when levels are high. When Clomid blocks these receptors, the hypothalamus perceives low estrogen and releases more GnRH to stimulate the pituitary.

Increased GnRH stimulates the anterior pituitary. The pituitary releases more follicle-stimulating hormone and luteinizing hormone. FSH stimulates ovarian follicle growth. LH triggers ovulation when the follicle matures. In men, the same mechanism increases LH and FSH. LH stimulates Leydig cells in the testes. Testosterone production rises. FSH supports spermatogenesis. This preserves fertility. Direct testosterone replacement therapy suppresses the hypothalamic-pituitary-gonadal axis and reduces sperm production.

Conditions Treated with Clomid

Doctors prescribe Clomid mainly for ovulation problems and female infertility. The FDA label covers women with ovulatory dysfunction who desire pregnancy. Common reasons include PCOS and irregular menstrual cycles. Some specialists add clomiphene to intrauterine insemination protocols for unexplained infertility.

Urologists also use Clomid off-label for men with low testosterone. Studies show 89 percent biochemical response. Total testosterone rises from 9 to 16 nmol per liter. Seventy-four percent of men report symptom improvement. Unlike testosterone replacement therapy, Clomid preserves fertility and testicular size.

Clomid is not for women who are already ovulating regularly without infertility. It is not for primary ovarian failure. It is not for uncontrolled thyroid or adrenal disease. Patients taking Metformin for PCOS or insulin resistance should tell their doctor before starting Clomid. Both drugs affect metabolic pathways and may require coordinated dosing.

Clomid Dosage and Strengths

Clomid comes in one strength: a 50 mg tablet. The first cycle uses 50 mg once daily. Take the tablet for 5 days in a row. Most doctors start on cycle day 3, 4, or 5. Day 1 means the first day of full menstrual bleeding.

If ovulation does not occur, the next cycle may use 100 mg daily. The FDA label sets 100 mg per day as the maximum. Reassess after 3 cycles without success. Most guidelines cap total use at 6 cycles. Longer use adds risk without clear benefit.

Scenario	Clomid dose	Length
First treatment cycle	50 mg once daily	5 days
No ovulation on 50 mg	100 mg once daily	5 days
FDA label maximum	100 mg per day	5 days per cycle
Off-label use in men	25 to 50 mg	Set by the prescriber

An ovulatory response occurs in 46 percent of women at 50 mg. Another 21 percent respond at 100 mg. If no ovulation occurs at 100 mg, the patient is considered clomiphene-resistant. Alternative therapies such as letrozole or gonadotropin injections are then considered.

For male hypogonadism, dosing is off-label. Common protocols use 25 mg every other day or 25 mg daily. Some clinicians use 50 mg every other day. Dose depends on baseline testosterone, body weight and response. Monitor total testosterone, free testosterone, luteinizing hormone, follicle-stimulating hormone and estradiol every 3 months. Adjust the dose to maintain testosterone in the mid-normal range. Avoid estradiol levels above 40 pg per mL. High estradiol causes gynecomastia and mood changes.

Missed Dose Instructions

Take the missed dose when you remember. If you miss an entire day during the 5-day cycle, contact your doctor. The cycle may need adjustment. Do not double the dose. Doubling increases the risk of ovarian hyperstimulation and multiple pregnancies. Resume the normal schedule as directed by your physician.

Side Effects of Clomid

Most side effects of Clomid stay mild and brief. FDA clinical trials report specific documented incidence rates for hot flashes, ovarian enlargement and abdominal discomfort during Clomid treatment. Serious adverse events include ovarian hyperstimulation syndrome, multiple pregnancies and visual disturbances.

Common Side Effects

Hot flashes lead the list and affect 10.4 percent of users. Ovarian enlargement appears in 13.6 percent of cycles and usually resolves on its own. Abdominal discomfort and bloating show up in 5.5 percent. Breast tenderness affects 2.1 percent. Nausea and vomiting affect 2.2 percent. Headache affects 1.3 percent. Visual symptoms affect 1.5 percent. Mood swings also occur. These effects fade after the cycle ends.

Serious Side Effects

Stop taking Clomid and contact a doctor immediately if you experience:

• Ovarian hyperstimulation syndrome: severe abdominal pain, rapid weight gain, shortness of breath, decreased urination. OHSS can be life-threatening. It occurs in 1 to 2 percent of Clomid cycles. Risk increases with higher doses and polycystic ovary syndrome.
• Multiple pregnancies: twins occur in 5 to 8 percent of Clomid pregnancies. Triplets or higher-order multiples occur in less than 1 percent. Multiple pregnancies increase preterm birth and maternal complications.
• Ovarian torsion: sudden severe pelvic pain, nausea, vomiting. A twisted ovary cuts off blood supply. Emergency surgery is required.
• Severe visual disturbances: persistent blurred vision, double vision, light sensitivity, scotomas. Stop Clomid immediately and see an ophthalmologist. Visual changes are usually reversible within days to weeks.
• Ectopic pregnancy: abdominal pain, vaginal bleeding, shoulder pain. Clomid increases ectopic risk slightly.
• Hepatitis or severe liver dysfunction: yellowing skin, dark urine, severe fatigue. Rare but serious.

Who Should Not Take Clomid

Do not take Clomid if you have liver disease or abnormal liver function tests. Do not take if you have uncontrolled thyroid or adrenal dysfunction. Do not take if you have ovarian cysts unrelated to polycystic ovary syndrome. Do not take if you have undiagnosed vaginal bleeding. Do not take if you have a history of ovarian cancer or endometrial cancer.

Do not take Clomid if you are pregnant. It carries a Category X warning. It may cause birth defects. Stop immediately if pregnancy occurs. Patients using other drugs metabolized in the liver should disclose them to their doctor. Concurrent use of multiple hepatic medications may stress liver function in susceptible patients.

Warnings and Precautions

Clomid increases the risk of ovarian hyperstimulation syndrome in susceptible patients. Monitor for rapid weight gain, abdominal distension and shortness of breath during each treatment cycle. Severe OHSS requires hospitalization with intravenous fluids and intensive monitoring. Ascites and pleural effusion may develop in severe cases.

Multiple pregnancies are a known risk. Ultrasound monitoring during the cycle identifies excessive follicle development. If more than 3 mature follicles develop, the cycle may be cancelled to avoid high-order multiples.

Visual disturbances require immediate discontinuation. Most cases resolve within days. Some persist for weeks. Permanent visual loss is rare but documented. Do not restart Clomid if visual symptoms occurred in a previous cycle.

Long-term use beyond 6 cycles may increase ovarian cancer risk. The FDA label notes that prolonged Clomid use may increase the risk of a borderline or invasive ovarian tumor. Data are limited but concerning. Limit therapy to 6 cycles unless compelling reasons exist.

Endometrial thinning occurs in some women. Clomid’s anti-estrogenic effect on the uterine lining may reduce implantation rates. This explains why ovulation rates exceed pregnancy rates. Compared to serotonin modulators, Clomid affects mood through hormonal pathways rather than serotonin reuptake inhibition. Patients with depression require careful monitoring during therapy.

Clomid Drug Interactions

The FDA label states that drug interactions with Clomid have not been formally documented in clinical trials. However, caution is warranted with medications that affect hepatic enzymes or bleeding risk. Always provide your doctor with a complete medication list before starting clomiphene therapy.

• Hepatic enzyme inducers (rifampin, phenytoin, phenobarbital): May reduce clomiphene levels. Monitor ovulatory response.
• Hepatic enzyme inhibitors (ketoconazole, erythromycin): May increase clomiphene levels. Monitor for side effects.
• Anticoagulants (warfarin): Case reports suggest altered INR. Monitor closely.
• Other fertility medications: Combining with gonadotropins increases OHSS and multiple pregnancy risk. Use only under specialist supervision.

Clomid and Pregnancy

Clomid is contraindicated during pregnancy. The FDA assigns Category X. Animal studies show increased embryo-fetal loss and structural malformations. Human epidemiologic data do not show a clear increased risk above background. However, the small number of cases limits statistical power. If pregnancy occurs during therapy, discontinue immediately and consult an OB-GYN.

Clomid does not pass into breast milk in significant amounts. However, it may reduce milk supply through its anti-estrogenic effects. Breastfeeding mothers should discuss risks and benefits with their doctor.

Overdose Information

Overdose symptoms include nausea, vomiting, flushing, abdominal pain, visual disturbances and ovarian enlargement. No specific antidote exists for clomiphene overdose. Treatment is supportive and requires medical supervision. Monitor ovarian size and liver function closely. Contact poison control at 1-800-222-1222 immediately.

Clomid vs Letrozole

Letrozole is the main alternative to clomiphene. A 2014 New England Journal of Medicine trial compared both drugs in 750 women with PCOS. Live birth rates reached 27.5 percent with letrozole versus 19.1 percent with Clomid. Twin rates also ran lower with letrozole. Letrozole for ovulation remains off-label in the US. Many specialists still start with Clomid because of its long safety record since 1967.

Letrozole causes fewer anti-estrogenic effects on the endometrium. Endometrial thickness is better preserved. Implantation rates may be higher. Letrozole has a lower multiple pregnancy rate. Twin rates are 3 to 5 percent versus 5 to 8 percent with Clomid. Letrozole carries a lower OHSS risk. It is often preferred for women with PCOS.

Clomid is more widely available. It has decades of safety data. Letrozole is newer but gaining preference in many fertility clinics. Both require prescription monitoring. Both are ineffective in primary ovarian failure.

Storage and Handling

Store Clomid at room temperature between 68 and 77 degrees Fahrenheit. Keep tablets dry and away from direct light. Skip the bathroom cabinet because of humidity. Keep the bottle out of reach of children and pets. Discard expired tablets through a pharmacy take-back program.

Frequently Asked Questions

Sources and References

• U.S. Food and Drug Administration – CLOMID (clomiphene citrate) Tablets Prescribing Information, NDA 016131
• U.S. National Library of Medicine, DailyMed – Clomiphene Citrate Tablets Drug Label, Updated October 2025
• PubMed – Krzastek SC et al. Long-Term Safety and Efficacy of Clomiphene Citrate for the Treatment of Hypogonadism. J Urol. 2019
• PMC – Huijben M et al. Clomiphene citrate for men with hypogonadism: a systematic review and meta-analysis. Andrology. 2022
• Legro RS et al. Letrozole versus Clomiphene for Infertility in the Polycystic Ovary Syndrome. New England Journal of Medicine, 2014; 371:119-129