Coenzyme Q10 (CoQ10) is increasingly discussed as a potential supplement to support fertility, yet many individuals remain uncertain about appropriate dosing and evidence. Whilst CoQ10 plays a vital role in cellular energy production and antioxidant protection, it is not a licensed fertility treatment in the UK and lacks universal clinical guidelines. Dosages studied for fertility typically range from 100 mg to 600 mg daily, depending on individual circumstances and whether the focus is male or female reproductive health. This article examines the evidence base, recommended dosages, timing considerations, and safety profile of CoQ10 supplementation in the context of fertility, helping you make informed decisions in consultation with your healthcare provider.

What Is CoQ10 and How Does It Support Fertility?

Coenzyme Q10 (CoQ10), also known as ubiquinone, is a naturally occurring antioxidant found in virtually every cell of the human body. It plays a crucial role in mitochondrial energy production, helping cells generate adenosine triphosphate (ATP), the primary energy currency required for cellular function. CoQ10 concentrations are high in organs with substantial energy demands, including the heart, liver, and kidneys.

In the context of fertility, CoQ10's antioxidant properties are thought to protect reproductive cells from oxidative stress—a condition where harmful free radicals damage cellular structures, including DNA. Oocytes (eggs) and sperm cells are especially vulnerable to oxidative damage due to their high metabolic activity and the extended time eggs spend in the ovaries. As women age, natural CoQ10 levels decline, which may contribute to reduced egg quality and mitochondrial dysfunction within oocytes.

For men, CoQ10 is present in seminal fluid and is believed to support sperm motility, morphology, and overall quality by enhancing mitochondrial function within sperm cells. The theoretical basis for CoQ10 supplementation in fertility centres on its potential to improve cellular energy production and reduce oxidative damage in reproductive cells, though this mechanistic plausibility has not yet translated into proven improvements in live birth rates.

In the UK, CoQ10 is regulated as a food supplement (not a licensed medicine), with oversight from the Food Standards Agency rather than the MHRA. It is not a licensed fertility treatment. The evidence base is evolving, and individuals considering supplementation should discuss this with their GP or fertility specialist to ensure it aligns with their overall reproductive health plan. When selecting a supplement, consider reputable UK or EU manufacturers with evidence of third-party quality testing.

Recommended CoQ10 Dosage for Fertility in the UK

There is no universally agreed dosage of CoQ10 specifically for fertility, and no UK clinical guidelines recommend it for this purpose. However, clinical studies examining potential fertility benefits have used dosages ranging from 100 mg to 600 mg daily, depending on individual circumstances and the specific fertility concern being addressed.

For women, particularly those undergoing assisted reproductive technology (ART) such as in vitro fertilisation (IVF), studies have typically used doses between 200 mg and 600 mg per day. Some research suggests that higher doses (around 600 mg daily) may be associated with improvements in ovarian response and egg quality, though evidence remains limited and not all studies show consistent benefits. Importantly, improvements in live birth rates have not been conclusively demonstrated.

For men with concerns about sperm quality, doses commonly range from 200 mg to 300 mg daily. Some trials have used up to 300 mg per day for periods of three to six months, reflecting the time required for a full cycle of sperm production (spermatogenesis), which takes approximately 74 days.

CoQ10 is available in two main forms: ubiquinone (the oxidised form) and ubiquinol (the reduced, active form). Ubiquinol is often marketed as more bioavailable, though both forms appear to be converted in the body. While ubiquinol may achieve higher plasma levels, clinical superiority for fertility outcomes remains unproven.

It is essential to consult a healthcare professional before starting CoQ10 supplementation, particularly if you are undergoing fertility treatment, taking other medications, or have underlying health conditions. Do not exceed the manufacturer's recommended dose without medical advice. Your GP or fertility specialist can provide personalised advice based on your medical history and treatment plan.

Evidence for CoQ10 in Male and Female Fertility

The evidence supporting CoQ10 supplementation for fertility is mixed and evolving, with some promising findings but also significant limitations in study design and population size.

Female fertility: Several small studies have suggested that CoQ10 may improve ovarian response in women undergoing IVF, particularly in those of advanced maternal age (typically over 35 years). A randomised controlled trial published in Fertility and Sterility found that women taking 600 mg of CoQ10 daily had improved ovarian response and a higher number of high-quality embryos compared to placebo. However, these studies are limited by small sample sizes, and larger, well-designed trials are needed to confirm these findings. There is currently no robust evidence that CoQ10 supplementation increases live birth rates, which is the most clinically meaningful outcome.

For women with conditions such as polycystic ovary syndrome (PCOS), some preliminary research suggests CoQ10 may improve metabolic parameters and ovarian function, though the evidence is insufficient to make firm recommendations.

Male fertility: The evidence for CoQ10 in male infertility is somewhat more established. Systematic reviews and meta-analyses have indicated that CoQ10 supplementation may improve sperm concentration, motility, and morphology in men with idiopathic infertility (infertility with no identifiable cause). A Cochrane review on antioxidants for male subfertility noted improvements in sperm parameters but highlighted that evidence for improved pregnancy or live birth rates remains limited.

It is important to recognise that whilst CoQ10 may support certain aspects of reproductive health, it is not a substitute for evidence-based fertility treatments such as ovulation induction, intrauterine insemination (IUI), or IVF. The National Institute for Health and Care Excellence (NICE CG156) does not currently include CoQ10 in its fertility guidelines, reflecting the need for further high-quality research.

When to Take CoQ10 and What to Expect

Timing and duration are important considerations when using CoQ10 for fertility. Because CoQ10 works at the cellular level to support mitochondrial function and reduce oxidative stress, it requires consistent use over an extended period to potentially exert beneficial effects.

For women, it is generally recommended to begin CoQ10 supplementation at least three months before attempting conception or starting fertility treatment such as IVF. This timeframe aligns with the maturation cycle of oocytes, which takes approximately 90 days. Some fertility specialists may suggest continuing supplementation throughout the treatment cycle. It is generally advisable to discontinue CoQ10 once pregnancy is confirmed unless specifically recommended by your healthcare provider.

For men, a minimum of three months of supplementation is typically advised, reflecting the 74-day cycle of sperm production plus additional time for sperm maturation and transport. Some studies have used treatment periods of up to six months.

CoQ10 is a fat-soluble supplement, meaning it is best absorbed when taken with food, particularly meals containing some dietary fat. Dividing the daily dose (for example, taking 200 mg twice daily rather than 400 mg once) may improve absorption and tolerability.

What to expect: CoQ10 supplementation is unlikely to produce immediate or dramatic changes. Any potential benefits develop gradually over weeks to months. It is important to maintain realistic expectations—whilst some individuals may experience improvements in reproductive parameters (such as sperm quality or ovarian response), others may see no measurable change. CoQ10 should be viewed as a complementary approach rather than a guaranteed solution.

Importantly, do not delay seeking medical advice about fertility concerns. According to NICE guidelines, couples should seek assessment if they have not conceived after 12 months of regular unprotected intercourse (or earlier if the woman is aged 36 or over, or if there are known fertility issues). Red flags warranting prompt medical attention include amenorrhoea (absence of periods for over 3 months), markedly irregular cycles, severe pelvic pain, history of pelvic inflammatory disease or endometriosis, prior chemotherapy, testicular disorders, or erectile/ejaculatory problems.

Safety Considerations and Interactions with Fertility Treatments

CoQ10 is generally considered safe and well-tolerated when used at recommended doses. Most people experience no adverse effects, though some may report mild gastrointestinal symptoms such as nausea, diarrhoea, or stomach upset. These effects are typically dose-dependent and may be minimised by taking CoQ10 with food or dividing the daily dose.

Other potential side effects, though uncommon, include:

• Headache

• Dizziness

• Insomnia (particularly if taken late in the day)

• Skin rash or itching

Serious adverse effects are rare in short-term studies, but long-term safety data are limited, and higher doses should only be used under medical supervision.

Drug interactions: CoQ10 may interact with certain medications. It can potentially reduce the effectiveness of warfarin (a blood-thinning medication). If you are taking warfarin, consult your GP before starting CoQ10 and arrange INR monitoring when starting or stopping supplementation. CoQ10 may have additive effects with antihypertensive medications, potentially enhancing blood pressure reduction. It may also affect glycaemic control in people with diabetes. Regular monitoring is advisable if you have these conditions.

Fertility treatments: There is no official evidence that CoQ10 interferes with standard fertility treatments such as ovulation induction medications (clomifene citrate, letrozole), gonadotrophins, or IVF procedures. However, it is essential to inform your fertility specialist about all supplements you are taking, as this allows for comprehensive treatment planning and monitoring.

When to seek advice: Contact your GP if you experience persistent or severe side effects. Patients undergoing chemotherapy or radiotherapy should consult their oncology team before taking antioxidant supplements. Pregnant or breastfeeding women should avoid CoQ10 unless specifically advised by a healthcare professional, as safety data in these populations are insufficient.

If you suspect you have experienced a side effect from CoQ10, you can report this through the MHRA Yellow Card Scheme, which monitors the safety of supplements and medications.

Frequently Asked Questions