Metformin, Clomid and letrozole for PCOS fertility treatment
Originally written by Zita West. Updated by femme to reflect current evidence-based PCOS fertility guidance.
PCOS can make conception more difficult when ovulation is infrequent or absent. Medicines such as letrozole, clomifene (often known by the brand name Clomid) and metformin can all have roles, but they do different jobs and are not interchangeable.
The correct treatment depends on whether ovulation is the main fertility problem and on the rest of the fertility assessment and testing picture. Our fertility consultation guide explains what that assessment can involve.
Why can PCOS affect fertility?
PCOS, now increasingly referred to as PMOS, is associated with ovulatory dysfunction and higher androgen levels. Some people also have insulin resistance. These features can make ovulation less regular, but PCOS does not mean pregnancy is impossible. Our guide to PCOS and egg quality separates ovarian reserve from egg quality.
For the wider condition, see our PCOS/PMOS guide.
PCOS fertility medicines compared
Letrozole
The 2023 International Evidence-based PCOS Guideline recommends letrozole as the preferred first-line medicine for anovulatory infertility in PCOS when there are no other infertility factors. It is prescribed and monitored by an appropriate clinician.
Clomifene / Clomid
Clomifene stimulates ovulation and remains an established fertility medicine. Depending on the individual situation, it may be used alone or in combination with metformin.
Metformin
Metformin improves insulin sensitivity and is commonly used for metabolic features of PCOS. It can also have a role in fertility treatment. But it is not simply an “egg quality” medicine, and the current international guideline does not recommend it as the preferred first-line medicine for ovulation induction.
Other fertility treatment
Gonadotrophins, ovarian surgery in selected cases and IVF can be considered when first-line ovulation treatment is unsuccessful or when another fertility factor makes assisted conception appropriate.
Metformin and Clomid together: why might they be prescribed?
Some people with PCOS are prescribed metformin and clomifene together. The rationale is that the medicines target different parts of the picture: metformin affects insulin sensitivity, while clomifene is used to stimulate ovulation.
That does not mean the combination is automatically better for everybody. Choice of medicine, dose and monitoring should come from the clinician managing fertility treatment.
Metformin vs Clomid: what is the difference?
Metformin is primarily an insulin-sensitising medicine. Clomid/clomifene is an ovulation-induction medicine. If somebody's main fertility problem is anovulation, the question is not simply which of the two is “stronger”. The current PCOS guideline places letrozole ahead of both as preferred first-line ovulation induction in the appropriate clinical setting.
PCOS fertility medication: common questions
Can metformin help you get pregnant with PCOS?
Metformin can have a role in fertility management for some people with PCOS, particularly where metabolic features are relevant, but it is not a guarantee of ovulation or pregnancy.
Can you take metformin and Clomid together?
They can be prescribed together in selected patients, but this should be decided and monitored by a fertility clinician rather than self-directed.
Is Clomid the best fertility medicine for PCOS?
Not under current international guidance. Letrozole is preferred first-line for anovulatory infertility in PCOS when no other infertility factors are present.
What if ovulation medicines do not work?
Further options can include gonadotrophins, selected surgical treatment or IVF, depending on the individual fertility assessment and previous response.
Metformin and Clomid together
Searches for metformin and Clomid often assume they do the same job. They do not: metformin primarily targets metabolic features and insulin sensitivity, while clomifene stimulates ovulation. They may be prescribed together in selected circumstances. Current international PCOS guidance generally prefers letrozole as first-line ovulation induction for anovulatory infertility when there are no other infertility factors.
Are there alternatives to metformin for PCOS?
That depends on why metformin is being considered. Lifestyle measures, other metabolic treatment and fertility medicines address different problems, so there is no single direct substitute. Treatment should be based on metabolic risk, symptoms, pregnancy plans and clinical assessment.
Lifestyle and supplements
A balanced diet, regular activity, sleep and weight management where relevant can support metabolic and reproductive health. They should not replace indicated fertility treatment or become a source of blame.
Inositol is widely marketed for PCOS. Current international guidance says it may be considered, but clinical benefits are limited and specific types or doses cannot be confidently recommended from the available evidence.
The bottom line
Metformin, Clomid and letrozole are different medicines with different roles. For PCOS-related anovulatory infertility, letrozole is now the preferred first-line medicine in the international guideline. Clomifene and metformin remain relevant in selected patients.
Fertility treatment should be based on the whole assessment rather than assuming PCOS explains every difficulty conceiving.
Further information
2023 International Evidence-based PCOS Guideline
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