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Ovulation Induction Pregnancy: Section 4.6: 'Clomid is not indicated during pregnancy. Although there is no evidence that Clomid has a harmful effect on the human fetus, there is evidence that Clomid has a deleterious effect on rat and rabbit fetuses when given in high doses to the pregnant animal.' To avoid inadvertent administration during early pregnancy, appropriate tests should be used during each treatment cycle to determine whether ovulation occurs, with a pregnancy test before the next course. It is not known whether clomifene citrate is excreted in human milk; clomifene may reduce lactation.

Clomifene

Brand names: Clomid, Serophene

Clomifene citrate is an oral selective oestrogen receptor modulator used to induce ovulation in anovulatory subfertility.

Adult dose

Dose: Ovulatory failure in women desiring pregnancy (only where ovulatory dysfunction is demonstrated): first course 50 mg (1 tablet of 50 mg) daily for 5 days. If ovulation appears not to have occurred after the first course, a second course of 100 mg daily (two 50 mg tablets given as a single daily dose) for 5 days.
Route: Oral
Frequency: Once daily for 5 days per course. First course: start at any time in a patient who has had no recent uterine bleeding; if progestin-induced bleeding is planned, or spontaneous uterine bleeding occurs before therapy, start on or about the fifth day of the cycle. A second course may be started as early as 30 days after the previous one.
Max: 100 mg/day for 5 days per course. SPC: 'Increase of the dosage or duration of therapy beyond 100 mg/day for 5 days should not be undertaken.'
Strength: Clomid 50 mg tablets, clomifene citrate 50 mg per tablet (SPC section 2). Indication (section 4.1): treatment of ovulatory failure in women desiring pregnancy; 'indicated only for patients in whom ovulatory dysfunction is demonstrated. Other causes of infertility must be excluded or adequately treated before giving Clomid.' When ovulation occurs at the first-course dose there is no advantage in increasing the dose in subsequent cycles. The majority of responders respond to the first course and 3 courses should constitute an adequate therapeutic trial; if ovulatory menses have not yet occurred the diagnosis should be re-evaluated, and treatment beyond this is not recommended in a patient who does not exhibit evidence of ovulation. Long-term cyclic therapy is not recommended: 'Efficacy and safety of clomifene for more than 6 treatment cycles have not been demonstrated.' Special care with lower dosage or duration of treatment is particularly recommended if unusual sensitivity to pituitary gonadotrophin is suspected, such as in polycystic ovary syndrome (section 4.2). Use the lowest dose consistent with expectation of good results to minimise abnormal ovarian enlargement (section 4.4). The SPC licenses clomifene only for women; it gives no male-infertility or paediatric regimen. Some sections of the product information we used were incomplete — check the full SPC.

Dose adjustments

Renal

The SPC (section 4.2) states no renal dose adjustment.

Hepatic

Contraindicated in patients with liver disease or a history of liver dysfunction (section 4.3); no reduced-dose regimen is given.

Dose independently re-sourced from UK Summary of Product Characteristics (SPC) via MHRA Products — clinician-reviewed. Always confirm against the product SmPC and your local formulary before prescribing.

Contraindications

  • Pregnancy (sections 4.3 and 4.6: 'Clomid is not indicated during pregnancy')
  • Liver disease or a history of liver dysfunction (section 4.3)
  • Hormone-dependent tumours (section 4.3)
  • Abnormal uterine bleeding of undetermined origin (section 4.3)
  • Ovarian cyst, except polycystic ovary, since further enlargement of the cyst may occur; patients should be evaluated for ovarian cyst prior to each course (section 4.3)

Side effects

  • More commonly reported in investigational studies (section 4.8): ovarian enlargement (13.6%), vasomotor flushes (10.4%), abdominal-pelvic discomfort (distention, bloating) (5.5%), nausea and vomiting (2.2%), breast discomfort (2.1%), visual symptoms (1.5%), headache (1.3%), intermenstrual spotting or menorrhagia (1.3%)
  • Adverse effects appeared dose-related, more frequent at the higher dose and with longer courses (section 4.8)
  • Ovarian Hyperstimulation Syndrome (OHSS), including with cyclic use or combination with gonadotropins; rapid progression to the severe form may occur if conception results (section 4.4)
  • Visual symptoms (blurring, spots or flashes, scintillating scotomata, partial or complete loss of vision); usually reversible but prolonged or irreversible disturbances have been reported, especially with increased dosage or duration (sections 4.4, 4.8)
  • Hypersensitivity reactions including anaphylaxis and angioedema (frequency not known) (section 4.8)
  • Multiple pregnancy (7.9% of 2369 Clomid-associated pregnancies in clinical studies) and increased chance of ectopic pregnancy (sections 4.4, 4.8)
  • New or exacerbated endometriosis; reduced endometrial thickness (frequency not known) (section 4.8)
  • Hypertriglyceridaemia reported post-marketing (section 4.4)
  • SCOPE NOTE: sections 4.4 and 4.8 are truncated at the source-fetch limit, so this list is partial

Interactions

  • Section 4.5 of the SPC states 'None stated.'

Monitoring

  • Use appropriate tests during each treatment cycle to determine whether ovulation occurs, and a pregnancy test before the next course (section 4.6)
  • Evaluate for the presence of ovarian cyst prior to each course of treatment (section 4.3)
  • Examine a patient who complains of abdominal or pelvic pain, discomfort or distension after taking Clomid (possible ovarian cyst); examination of enlarged ovaries must be very cautious (section 4.4)
  • If any visual symptoms occur, discontinue treatment and perform ophthalmologic evaluation (section 4.4)
  • Periodic monitoring of plasma triglycerides may be indicated in patients with pre-existing or family history of hyperlipidaemia or on higher than recommended dose or longer duration (section 4.4)

Clinical monograph

How it works

By blocking hypothalamic oestrogen receptors it disrupts negative feedback, increasing gonadotrophin-releasing hormone and pituitary FSH and LH output to stimulate follicular development.

Prescribing in practice

  • There is an increased risk of multiple pregnancy and of ovarian hyperstimulation syndrome, so use should be supervised with cycle monitoring.
  • Treatment is given for a limited number of cycles and prolonged or repeated courses are not recommended because of concern about ovarian effects.
  • Visual disturbances are a recognised effect and treatment should be stopped if they occur.

Monitoring

Monitor the ovarian response, ideally with ultrasound, to guide treatment and reduce the risk of multiple pregnancy and hyperstimulation.

Counselling the patient

  • Be aware of an increased chance of twins or higher-order pregnancy.
  • Stop the medicine and seek advice if you experience visual symptoms such as blurring or flashes.
  • Report severe abdominal pain or bloating, which may indicate ovarian overstimulation.

Evidence & guidelines

Clomifene is a long-established first-line ovulation-induction agent; treatment should follow specialist fertility guidance and the SPC.

Reference: ESHRE/ASRM PCOS Guidelines 2023; NICE Fertility NG156; Drug verified in RxNorm (NLM); confirm dosing against the manufacturer SPC (eMC). Verify against your local formulary and current prescribing references before prescribing. The structured dose values shown have been reviewed by a clinician. Monograph status: clinician-reviewed (2026-07-04).

Related

Curated clinical cross-links plus same-class fallbacks.

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