Coenzyme Q10 (CoQ10) is a popular supplement amongst women trying to conceive, particularly those undergoing fertility treatment or of advanced maternal age. Whilst some research suggests potential benefits for egg quality, knowing when to stop taking CoQ10 for fertility is crucial for safe supplementation. In the UK, CoQ10 is classified as a food supplement rather than a licensed fertility medicine, and neither NICE nor the HFEA routinely recommend it. This article explores the evidence around CoQ10 timing, when to discontinue supplementation during fertility treatment, and the importance of consulting your fertility specialist for personalised guidance.

How CoQ10 Supports Fertility and Egg Quality

Coenzyme Q10 (CoQ10) is a naturally occurring antioxidant found in every cell of the body, playing a crucial role in cellular energy production within the mitochondria. In the context of fertility, CoQ10 has gained attention for its potential to support egg quality, particularly in women of advanced maternal age or those undergoing assisted reproductive technology (ART) such as in vitro fertilisation (IVF).

As women age, the quality and quantity of eggs decline, partly due to mitochondrial dysfunction and increased oxidative stress within oocytes (egg cells). CoQ10 supplementation aims to address this by:

• Enhancing mitochondrial function – potentially providing energy required for egg maturation

• Reducing oxidative damage – theoretically protecting eggs from free radical damage

• Potentially affecting ovarian reserve markers – though evidence for this is inconsistent

Some clinical studies have investigated CoQ10 supplementation (typically 200–600 mg daily in research settings) for ovarian response during IVF cycles. However, it's important to understand that the evidence remains limited by small study sizes and varying methodologies. While some studies suggest modest improvements in certain fertility parameters, there is currently insufficient evidence to confirm benefits for live birth rates.

It is important to note that CoQ10 is a food supplement in the UK, not a licensed medicine for fertility treatment. Neither the National Institute for Health and Care Excellence (NICE) nor the Human Fertilisation and Embryology Authority (HFEA) routinely recommend antioxidant supplements for women to improve fertility outcomes. The only supplement routinely recommended for women trying to conceive is folic acid (400 micrograms daily).

Women considering CoQ10 for fertility should discuss this with their GP or fertility specialist to ensure it is appropriate for their individual circumstances and does not interact with other medications or treatments they may be receiving.

When to Stop Taking CoQ10 During Fertility Treatment

Determining the optimal time to discontinue CoQ10 during fertility treatment requires individualised guidance from your fertility specialist, as there is no universally agreed protocol or formal UK guidance on this supplement.

Upon confirmation of pregnancy is the most frequently recommended stopping point in clinical practice. Once a positive pregnancy test is confirmed (typically around 4–5 weeks gestation), many fertility specialists advise discontinuing CoQ10 supplementation. This recommendation stems from:

• Limited safety data – there is insufficient evidence regarding CoQ10 supplementation throughout pregnancy, particularly in the first trimester when organ development occurs

• Completed therapeutic window – CoQ10's theoretical benefit relates to egg quality before conception

• Precautionary principle – minimising unnecessary supplementation during early pregnancy unless specifically indicated

During IVF cycles, timing may differ slightly. Some clinics recommend continuing CoQ10 until embryo transfer, whilst others suggest stopping at egg collection (oocyte retrieval). This variation reflects the absence of standardised guidelines rather than evidence of harm.

Before starting ovulation induction medications, your fertility team may review all supplements. Whilst CoQ10 does not typically interfere with fertility medications such as clomifene citrate or gonadotropins, your specialist may adjust the regimen based on your specific protocol.

If you've been trying to conceive for 12 months without success (or 6 months if you're over 36), the NHS recommends seeking advice from your GP, regardless of supplement use. Remember that taking supplements should not delay seeking appropriate fertility assessment.

Always follow your fertility clinic's specific guidance, as protocols may vary based on individual patient factors, treatment type, and emerging evidence in this evolving field of reproductive medicine.

Signs You Should Discontinue CoQ10 Supplementation

Whilst CoQ10 is generally well-tolerated, certain signs and symptoms warrant immediate discontinuation and consultation with your healthcare provider. Being aware of these indicators ensures safe supplementation during your fertility journey.

Gastrointestinal disturbances are the most commonly reported adverse effects of CoQ10 supplementation. These may include:

• Nausea or vomiting

• Diarrhoea or loose stools

• Abdominal discomfort or cramping

• Loss of appetite

• Heartburn or acid reflux

If these symptoms are mild and transient, taking CoQ10 with food or reducing the dose may help. However, persistent or severe gastrointestinal symptoms should prompt discontinuation and medical review.

Allergic reactions, though rare, require immediate cessation of CoQ10. Warning signs include skin rashes, itching, facial swelling, or difficulty breathing. If you experience facial swelling or breathing difficulties, call 999/112 immediately or go to A&E.

Interactions with medications may necessitate stopping CoQ10. If you are prescribed:

• Warfarin or other anticoagulants – CoQ10 may reduce their effectiveness; do not start or stop CoQ10 without medical advice and arrange INR monitoring if you take warfarin

• Blood pressure medications – CoQ10 can lower blood pressure, potentially causing hypotension when combined with antihypertensives

• Cancer treatments – if you are receiving chemotherapy or radiotherapy, consult your oncology team before taking any antioxidant supplements including CoQ10

Unusual symptoms such as persistent headaches, dizziness, insomnia, or fatigue should be reported to your GP or fertility specialist. Any new or concerning symptoms during supplementation deserve professional evaluation.

If you become pregnant unexpectedly whilst taking CoQ10 outside of a monitored fertility treatment cycle, contact your GP or midwife promptly to discuss whether to continue supplementation.

If you experience any suspected side effects from CoQ10, you can report them through the MHRA Yellow Card Scheme (yellowcard.mhra.gov.uk).

Consulting Your Fertility Specialist About CoQ10

Open communication with your fertility specialist is essential when considering or taking CoQ10 supplementation. A collaborative approach ensures that supplementation aligns with your overall fertility treatment plan and individual health needs.

Before starting CoQ10, schedule a consultation to discuss:

• Appropriateness for your situation – your specialist can advise whether CoQ10 might be relevant based on your specific fertility factors

• Dosage considerations – research studies have used doses ranging from 200–600 mg daily, but your specialist can discuss what might be appropriate in your circumstances

• Duration of pre-treatment – some research suggests taking CoQ10 for 2–3 months before conception attempts or IVF cycles, though optimal timing remains unclear

• Product quality – as a food supplement, CoQ10 products vary in quality; choose products from reputable UK/EU suppliers with quality assurance

During treatment, maintain regular dialogue about:

• Any side effects or concerns

• Changes to your medication regimen

• Results of fertility investigations (e.g., AMH levels, antral follicle count)

• Timing of discontinuation relative to your treatment protocol

Questions to ask your fertility specialist include:

• At what point in my treatment cycle should I stop taking CoQ10?

• Are there any interactions with my prescribed fertility medications?

• Should my partner also consider CoQ10 for male factor fertility? (Note that while some studies suggest improved semen parameters with CoQ10, evidence for improved live birth rates remains uncertain)

• What evidence supports CoQ10 use in my specific situation?

• What other lifestyle changes might improve my fertility outcomes?

Remember that if you've been trying to conceive for 12 months without success (or 6 months if you're over 36), the NHS recommends seeking advice from your GP. Taking supplements should not delay appropriate fertility assessment and treatment.

Your specialist can help integrate any supplements into a comprehensive fertility plan that addresses all relevant factors affecting your reproductive health, while ensuring you're taking the recommended 400 micrograms of folic acid daily as advised by the NHS for all women trying to conceive.

Frequently Asked Questions