Enclomiphene Side Effects: A Cautious, Evidence-Based Guide

Enclomiphene side effects most commonly reported in men may include headache, dizziness, nausea or abdominal discomfort, hot flashes, mood changes and an increase in estradiol, but the supporting data is limited and long-term safety has not been established. Enclomiphene is the trans-isomer of clomiphene citrate and a non-steroidal selective estrogen receptor modulator (SERM). It is not FDA-approved for any use, and in the United States it is available only as a compounded prescription, used off-label for male secondary hypogonadism. Because no approved enclomiphene label exists, much of the recognized safety information is drawn from the FDA-approved clomiphene citrate label, which describes additional class-level risks that are worth understanding before starting therapy.

What are the most common enclomiphene side effects?

In Phase II and III trials in men, enclomiphene’s adverse-event rate was reported as low and broadly similar to placebo. The effects most commonly described in the older enclomiphene (Androxal) trial program from Repros Therapeutics, including the work of Wiehle and colleagues, were headache (reported at roughly 3 percent), dizziness (reported at roughly 1 percent), and abdominal or gastrointestinal discomfort, along with elevated estradiol. These come from small studies and should not be read as robust, settled rates. A separate 2025 systematic review and meta-analysis of SERM therapy for male hypogonadism reported no serious adverse events but explicitly states that it is underpowered with regard to safety endpoints, which is why long-term safety cannot be considered established. In other words, a low signal in small, short studies is not the same as a clean long-term safety record, and individual results vary.

It is also worth noting that, as a component of clomiphene, enclomiphene falls under WADA Section S4 (Hormone and Metabolic Modulators) and is prohibited in competitive sport, according to Operation Supplement Safety. Athletes subject to testing should treat this as material safety and eligibility information and discuss it with a licensed provider.

How does the clomiphene label inform enclomiphene’s risk profile?

Because enclomiphene and clomiphene are closely related SERMs, regulators and clinicians often look to the FDA-approved clomiphene citrate label for class-level risk context. Importantly, the clomiphene label reflects use in female fertility, so several listed reactions, including ovarian enlargement, ovarian hyperstimulation and abnormal uterine bleeding, are female-fertility events and do not apply to male patients. The table below separates what has been observed in the small male enclomiphene datasets from the broader clomiphene-label risks that are cited at the class level. None of these clomiphene rates should be read as enclomiphene’s measured rates in men.

Category	Examples	Source and important caveats
Commonly reported in men (enclomiphene)	Headache (~3%), dizziness (~1%), abdominal/GI discomfort, elevated estradiol	From small Androxal/Wiehle-era Phase II/III datasets; rate reported as low and similar to placebo; safety endpoints underpowered, long-term safety not established
Common reactions on the clomiphene label (class context)	Vasomotor flushes/hot flashes (10.4%), abdominal-pelvic discomfort (5.5%), nausea and vomiting (2.2%), breast discomfort (2.1%), visual symptoms (1.5%), headache (1.3%)	From the FDA clomiphene citrate label in a female-fertility population; not enclomiphene’s measured rates in men
Serious or class-level risks to be aware of	Visual disturbances (which may be prolonged or irreversible), clot-related events (pulmonary embolism, thrombophlebitis, phlebitis), mood changes	Described on the clomiphene label; some visual disturbances are reported as prolonged and may occur after stopping the drug. Deep venous thrombosis appears on the label only as a complication of female ovarian hyperstimulation syndrome
Female-fertility events (NOT applicable to men)	Ovarian enlargement (13.6%), ovarian hyperstimulation, abnormal uterine bleeding	Specific to female fertility use; listed here only to avoid misattribution

How serious can visual side effects be?

Visual symptoms deserve careful attention. The clomiphene citrate label notes that visual symptoms such as blurring, spots, flashes or shimmering vision tend to increase in incidence with higher total dose or longer duration. These symptoms are usually reversible, but the label specifically warns that cases of prolonged visual disturbance have been reported, some occurring after the drug is discontinued, and that these may be irreversible, especially with increased dosage or duration. Reported visual disorders on the label include optic neuritis, retinal thrombosis or hemorrhage, macular edema, and temporary or prolonged loss of vision.

A 2011 review in Gynecologic and Obstetric Investigation reported that clomiphene may predispose to central retinal vein occlusion (CRVO), but the authors stated a causal link is not confirmed and that more research is needed. The takeaway is not to assume causation, and not to assume any new vision change is harmless. Any new visual disturbance is a reason to stop and contact a licensed provider promptly.

What about blood clots and mood changes?

The clomiphene citrate label’s postmarketing cardiovascular reports include clot-related events such as pulmonary embolism, thrombophlebitis and phlebitis. Deep venous thrombosis and thromboembolism are mentioned on the label only within the context of ovarian hyperstimulation syndrome, a female-fertility complication, rather than as general adverse reactions. Taken together, this is a class-level signal rather than a measured enclomiphene rate in men, but it is material safety information that a provider should weigh against your personal risk factors. You can review the clotting and visual warnings in the FDA-approved clomiphene prescribing information.

The clomiphene label’s postmarketing reports also include mood-related effects such as anxiety, irritability, mood changes and, rarely, psychosis, as well as migraine. If you notice significant changes in mood, persistent headaches or migraine, these are worth discussing with your provider.

When should you stop enclomiphene and call a provider?

This is educational information, not a substitute for individualized medical guidance, and you should follow your own provider’s instructions. In general, the clomiphene label and class context suggest that the following warrant stopping and contacting a licensed provider:

• Any new visual disturbance, including blurring, spots, flashes, shimmering vision or loss of vision, because some visual effects may be prolonged or irreversible.
• Possible signs of a blood clot, such as leg swelling or pain, sudden shortness of breath, or chest pain. Sudden shortness of breath or chest pain may signal a medical emergency and may warrant immediate care.
• Significant or worsening mood changes, severe headache or migraine, or any symptom that feels serious or unexpected.

Your provider can help determine whether a symptom is related to therapy and what monitoring may be appropriate.

Is compounded enclomiphene FDA-approved?

No. Enclomiphene citrate has never been FDA-approved for any use. Its developer, Repros Therapeutics, received a Complete Response Letter from the FDA in late 2015 for the brand-name product Androxal in secondary hypogonadism, with the agency indicating the Phase 3 study design was no longer adequate to demonstrate clinical benefit and that additional trials were needed. Those trials were never completed, and the drug was never approved. In June 2022, the FDA Pharmacy Compounding Advisory Committee (PCAC) voted against adding enclomiphene citrate to the final 503A Bulks List. As of the FDA list updated May 14, 2026, enclomiphene citrate remains in 503A Category 1 (Under Evaluation) and has not been added to the final, approved 503A bulks list, so its status is unsettled. A separate January 2025 FDA guidance ended the Category 1, 2 and 3 system for newly nominated 503B (outsourcing-facility) substances, which is a different statutory pathway from the 503A list under which compounded enclomiphene is prescribed. Because the status can change, confirm current standing against the latest FDA bulk drug substances list. None of this implies regulatory endorsement of the compounded product.

Frequently asked questions

What are the most common side effects of enclomiphene?

In small studies in men, the most commonly reported enclomiphene side effects may include headache, dizziness, and abdominal or gastrointestinal discomfort, along with elevated estradiol. Reported rates were low and broadly similar to placebo, but the datasets are small and long-term safety has not been established, so individual results vary.

Can enclomiphene cause vision problems?

The closely related clomiphene label warns of visual symptoms such as blurring, spots and flashes that may increase with higher dose or longer duration. While often reversible, some visual disturbances have been reported as prolonged, may occur after stopping the drug, and may be irreversible. Any new visual disturbance is a reason to stop and contact a licensed provider.

Does enclomiphene increase the risk of blood clots?

The clomiphene citrate label’s postmarketing cardiovascular reports include clot-related events such as pulmonary embolism, thrombophlebitis and phlebitis; deep venous thrombosis appears on the label only as a complication of female ovarian hyperstimulation syndrome. This is a class-level signal, not a measured enclomiphene rate in men, but it is material safety information your provider should weigh against your personal risk factors. Seek care for leg swelling or pain, sudden shortness of breath, or chest pain.

Is enclomiphene FDA-approved?

No. Enclomiphene is not FDA-approved for any use. In the United States it is available only as a compounded prescription and is used off-label in men. The FDA Pharmacy Compounding Advisory Committee voted against adding it to the final 503A Bulks List in 2022, and as of the FDA list updated May 14, 2026 it remains in 503A Category 1 (Under Evaluation), so its status is unsettled.

Is long-term enclomiphene use considered safe?

Long-term safety has not been established. A 2025 systematic review reported no serious adverse events but described the evidence as underpowered for safety endpoints. Short, small studies cannot confirm long-term safety, so ongoing care and monitoring with a licensed provider are important.