TL;DR
Coenzyme Q10 (ubiquinone/ubiquinol) is involved in mitochondrial energy production, and the body's natural levels decrease with age. This led to the hypothesis that supplementation might slow mitochondrial-related egg aging. One animal study (Aging Cell, 2015) supports this mechanism – in mice, not humans.
For women with diminished ovarian reserve, the most significant randomized study to date (Reproductive Biology and Endocrinology, 2018, n=169) showed improved intermediate markers under Q10 – fewer canceled cycles, more embryos suitable for storage – but no statistically significant difference in pregnancy or live birth rates. A meta-analysis (Journal of Assisted Reproduction and Genetics, 2020, 449 women) found a higher clinical pregnancy rate (28.8% vs. 14.1%), but likewise no effect on live births.
For men, a recent meta-analysis (2025, 781 participants) showed improved sperm parameters. However, the joint US guideline from AUA and ASRM still rates supplementation for male infertility as having "questionable clinical benefit." This article evaluates what that means for your decision – without making promises that the data cannot support.
Important medical note
If pregnancy does not occur after 12 months of regular, unprotected intercourse under the age of 35 (or after 6 months once age 35 is reached), a gynecological or andrological evaluation should be sought. This applies regardless of whether supplements are being taken.
Dietary supplements like Coenzyme Q10 are not medication and do not replace fertility treatment. Any potential or existing pregnancy, anticoagulant therapy (e.g., warfarin/phenprocoumon), or other long-term medication should be discussed with a doctor before taking higher doses of Q10.
Why egg quality is a topic at all
A woman's fertility is not constant over decades; it decreases noticeably from the mid-30s and significantly from the early 40s – not because there are "fewer" eggs, but because an increasing proportion of the remaining eggs exhibit chromosomal errors with age and are more difficult to fertilize. The American Society for Reproductive Medicine (ASRM) estimates the per-cycle probability of a natural pregnancy for a healthy 30-year-old at around 20%; at age 40, it is under 5% per cycle.
→ Source: American Society for Reproductive Medicine – Age and Fertility (Patient Education Booklet)
A central biological factor behind this decline is the egg cell's mitochondria – the "power plants" that supply energy for maturation, fertilization, and early cell division. As age increases, their functionality decreases while oxidative stress increases. Coenzyme Q10 is a naturally occurring building block of this mitochondrial energy chain – and because its levels also drop with age, the idea of supplementing it is intuitive. Whether it is the convincing lever it is often held to be in many fertility forums and guidebooks can only be verified by actual study data.
Ubiquinone and Ubiquinol: two forms, one active ingredient
Coenzyme Q10 is available in two chemical forms that are converted into each other in the body: ubiquinone (the oxidized, classic, and usually cheaper form) and ubiquinol (the reduced, active form, which is actually used in almost all cellular processes). Manufacturers of ubiquinol supplements often advertise better absorption via the gut – a plausible advantage, though not consistently proven in direct comparison studies, especially since healthy adults can efficiently convert oxidized ubiquinone into ubiquinol in the body.
| Feature | Ubiquinone | Ubiquinol |
|---|---|---|
| Form | Oxidized; classic, most researched form | Reduced; biologically active form actually used by the cell |
| Used in fertility RCTs | Yes – e.g., in the DOR study by Xu et al. 2018 | Yes – e.g., in several studies included in the Florou meta-analysis 2020 |
| Practical assessment | Usually cheaper; no proven efficacy gap compared to ubiquinol for healthy adults | Usually more expensive; theoretical absorption advantage, which has not been cleanly tested against ubiquinone in direct human fertility trials |
Before supplementing: what solid diagnostics can show
Before Coenzyme Q10 or other supplements can be sensibly evaluated, a baseline assessment is necessary. For women, this usually includes determining Anti-Müllerian Hormone (AMH) levels and counting antral follicles via ultrasound as a marker of ovarian reserve; studies such as those by Xu et al. 2018 also stratify patients according to the POSEIDON classification, which combines age and ovarian reserve to consistently define "low-prognosis" patients. For men, the sperm analysis (semen analysis) forms the basis; in the 6th edition of its laboratory manual (2021), the WHO updated the lower reference values – for example, a sperm concentration of at least 16 million/ml and a progressive motility of at least 30% (5th percentile in each case).
→ Source: WHO laboratory manual for the examination and processing of human semen, 6th edition (2021)
VEYT-Tip: A Q10 product does not replace diagnostics. Those under fertility stress for months often benefit more from an early AMH test or semen analysis than from choosing the "right" supplement – because only the findings will reveal whether a factor exists for which Q10 was studied (e.g., diminished ovarian reserve).
What research actually shows for women
The mechanistic foundation: a mouse study, not a human study
The most frequently cited foundational study on Q10 and egg aging comes from Ben-Meir et al. (2015). In older mice, Q10 supplementation normalized litter size reduced by aging, increased ATP production and oxygen consumption of egg mitochondria, and reduced spindle apparatus and chromosomal errors to a level barely distinguishable from young animals.
These results are often repeated in guides as if they were already proven in humans. In fact, this is a mouse study with supplementary cell culture data – an important and plausible indication of a potential mechanism, but no substitute for controlled studies on women trying to conceive. Those only followed in the years thereafter.
Practical consequence: The biological mechanism is well-founded – this justifies why researchers tested Q10 in humans at all, but it does not in itself prove an effect in humans. If you encounter "studies show" claims online without sources, you should specifically ask whether a mouse or human study is being referred to.
Xu et al. 2018: The most informative RCT to date on diminished ovarian reserve
A Chinese research team examined 169 young women (under 38) with diminished ovarian reserve according to POSEIDON Group 3 undergoing IVF/ICSI in a randomized controlled trial: 76 received Coenzyme Q10 before stimulation, 93 received no pretreatment.
With Q10 pretreatment, significantly fewer treatment cycles had to be canceled due to poor response (8.33% vs. 22.89%; p = 0.04), and embryos were more frequently available for cryopreservation (18.42% vs. 4.3%; p = 0.012). The fertilization rate in the Q10 group was 67.49%. For the endpoints ultimately decisive for couples – clinical pregnancy rate and live birth rate – there was a trend in favor of Q10, but it did not reach statistical significance.
Limitations: Single-blind instead of double-blind, a single center, no placebo for the control group (instead, "no pretreatment"), and a relatively small sample size for hard endpoints like live birth. The authors themselves classify the results as an improvement in intermediate steps, not a proven effect on the live birth rate.
Practical consequence: For women with confirmed diminished ovarian reserve who are planning IVF/ICSI treatment anyway, this is the most relevant available human study – it justifies an informed attempt, but not a promise of a higher chance of pregnancy.
Florou et al. 2020: What pooled data from five RCTs show
A systematic review in the Journal of Assisted Reproduction and Genetics summarized five randomized studies with a total of 449 women undergoing assisted reproduction (215 on Q10, 234 on placebo or no treatment).
The authors found a statistically significantly higher clinical pregnancy rate under Q10 (odds ratio 2.44; 95% confidence interval 1.30–4.59; p = 0.006). For the live birth rate – the endpoint that actually matters to couples – there was no significant difference (OR 1.67; 95% CI 0.66–4.25; p = 0.28), nor was there for the miscarriage rate. This is a pattern that occurs frequently in fertility research: a dietary supplement improves an intermediate step (here: the presence of a positive pregnancy test/fetal sac confirmed by ultrasound) without this consistently resulting in a live-born child at the end of the pregnancy – usually because the studies are simply too small and too short to statistically capture differences in rarer, later endpoints like live birth.
Practical consequence: The statement "Q10 increases the pregnancy rate" is covered by this meta-analysis. The statement "Q10 increases the chance of having a baby" is not according to the current data – this difference should remain visible in every honest evaluation.
For men: improved sperm parameters, but still little endpoint evidence
For men with idiopathic (unexplained) subfertility, a current systematic review is also available: nine randomized studies with 781 participants (430 on Q10, 351 controls).
Q10 significantly improved sperm concentration (mean difference +10.22 million/ml; 95% CI 3.51–16.93; p = 0.003) and total motility (mean difference +4.95%; 95% CI 1.15–8.75; p = 0.01) compared to control groups. For the pregnancy rate, the authors reported an odds ratio of 6.02 (95% CI 1.97–18.41; p = 0.002) – however, the analysis for this endpoint is based on significantly fewer studies with a smaller total sample size, making the estimate more uncertain than the impressive number suggests at first glance. Side effects in the included studies were rare and mostly mild (including nausea, headache, heartburn).
Practical Consequence: For sperm parameters as an intermediate step, the evidence in men has become quite consistently positive. For the question that matters most to a couple—does this lead to more pregnancies and live births—the data remains thinner than individual odds ratios might suggest.
What is best supported from today's perspective – and what that means for Q10
Before considering Coenzyme Q10, it is worth looking at the basic measures for which the evidence is generally much more robust: adequate folic acid intake before and during early pregnancy to lower the risk of neural tube defects, maintaining a body weight in the healthy range, avoiding smoking and alcohol, as well as an overall balanced diet. In guidelines and large cohort studies, these factors are much more consistently associated with better fertility outcomes than any individual dietary supplement. More on this in the VEYT guide Nutrition for Fertility and in the guide Folic Acid in Pregnancy.
Within the realm of dietary supplements, coenzyme Q10 occupies a middle ground: It is not "proven" by large, placebo-controlled studies with live birth as the primary endpoint, but it possesses more and more consistent intermediate-step evidence than many other supplements circulating in fertility forums. For safety: Following the doses used in studies (200–600 mg daily for 1–3 months), side effects were mostly mild (gastrointestinal complaints, occasional headaches); the potential interaction with blood thinners like warfarin is particularly relevant, which is why medical consultation should be mandatory if taking long-term medication—especially as soon as a pregnancy occurs. A more detailed classification of the general health risks of coenzyme Q10—for example, in cardiovascular diseases or in older age—detached from the fertility context, is provided in the VEYT guide Coenzyme Q10: Health Risks.
Other antioxidants for fertility: weaker or less consistently supported
Q10 is by far not the only substance sold under the label "antioxidant for egg quality." Myo-inositol has been studied primarily in women with PCOS-related subfertility—more on this in the VEYT guide PCOS: Nutrition and Insulin Resistance. N-acetylcysteine (NAC), melatonin, and vitamin E are also discussed in smaller studies regarding egg or sperm quality, though usually with smaller sample sizes, shorter study durations, and less consistent results than for Q10. The joint AUA/ASRM guideline on male infertility cautiously evaluates the entire group of supplements—antioxidants included—as a measure with "questionable clinical benefit," even if they are generally considered harmless.
→ Source: AUA/ASRM Guideline: Diagnosis and Treatment of Infertility in Men, Part II
Common assumptions put to the practical test
"You must take Q10 for at least three months, otherwise it's useless"
The pretreatment times used in studies are usually between 30 and 90 days because an egg maturation cycle takes about three months. However, this is a study convention, not a proven biological minimum—and no study shows that a planned fertility treatment should be postponed just to "complete" this period.
"Higher doses always work better"
In the cited studies, daily doses between 200 and 600 mg were used, without a clear dose-response relationship being proven for hard endpoints. The German Federal Institute for Risk Assessment (BfR) also notes that at doses up to 300 mg, isolated adverse effects such as nausea, heartburn, or diarrhea have been observed.
"Q10 works the same for every woman wanting to conceive"
The most meaningful study was specifically conducted with young women with proven reduced ovarian reserve—not women without an identifiable fertility factor. For couples without a diagnosed factor, it is unclear whether the observed effect carries over at all.
"If it works in mice, it also works in humans"
The mouse study by Ben-Meir et al. provided the biological impetus for human research but is not itself proof of efficacy in humans. Animal studies and controlled human studies answer different questions and should not be mixed in reporting.
Evidence overview: Coenzyme Q10 and related measures for fertility
| Approach | Evidence base | Relevant for whom | What does not follow |
|---|---|---|---|
| Q10 for reduced ovarian reserve | RCT (n=169, 2018): fewer cycle cancellations, more cryo-embryos; no sign. effect on pregnancy/live birth | Young women with diagnosed DOR before IVF/ICSI | No proven effect on the baby-take-home rate |
| Q10 in ART general | Meta-analysis (5 RCTs, n=449, 2020): higher clin. pregnancy rate (28.8% vs. 14.1%), no effect on live birth | Women in IVF/ICSI treatment | No evidence for natural conception without ART |
| Q10 in male subfertility | Meta-analysis (9 RCTs, n=781, 2025): more sperm, better motility; pregnancy data based on few studies | Men with unexplained subfertility | No replacement for andrological clarification |
| Mechanistic animal data (Ben-Meir 2015) | Mouse model: Restoration of mitochondrial function and litter size in aging | Explains the potential mechanism | No proof of efficacy in humans |
| AUA/ASRM guideline position | Supplements in male infertility overall classified as "questionable clinical benefit" (Grade B, conditional) | Classification of overall evidence from a urological/reproductive medicine perspective | Not a general ban – but also no recommendation as standard therapy |
| Folic acid, weight, smoking cessation | Significantly broader and more consistently supported in guidelines/cohort studies than individual antioxidants | All women wishing to conceive | Does not replace clarification if pregnancy does not occur |
| Other antioxidants (NAC, melatonin, Vit. E) | Smaller, inconsistent studies; generally less well-supported than Q10 | Individual consultation in a treatment context | No flat-rate replacement or addition without medical coordination |
This table summarizes publicly available evidence and does not replace individual medical or reproductive medicine advice.
VEYT Coenzyme Q10 check for fertility: 5 steps
- Clarify first, then supplement: If pregnancy does not occur (12 months, or 6 months if over 35), have your AMH level or semen analysis determined before targeted supplementation.
- Set realistic expectations: Based on current data, Q10 is at best a support for intermediate steps—not a proven lever for a higher live birth rate.
- Base dosage on the study situation: 200–600 mg daily over the last one to three months before a planned treatment are the frameworks most frequently used in studies—not an official standard dose.
- Clear interactions and pregnancy with a doctor: Especially with blood thinners, blood pressure medication, or as soon as a pregnancy test is positive.
- Do not neglect basic measures: Folic acid, healthy body weight, avoiding smoking and alcohol are, according to current evidence, the more reliable levers—Q10 can at most supplement, not replace them.
The VEYT products for this article
For this topic, we are consciously showing only a single, directly suitable product from our range—and are currently omitting the recommendation of a folic acid or "fertility complex" preparation because such a product is currently not available in our catalog. Those looking specifically for folic acid will find the relevant required values in the linked VEYT guide above.
VEYT Coenzyme Q10 200 mg (60 Softgels)
200 mg coenzyme Q10 per softgel, made in Germany. This dose is above the amount of 100 mg/day intended in Germany without a special warning—anyone taking blood thinners or blood pressure medication, or who is pregnant or could be pregnant, should consult a doctor beforehand.
To the product →Dietary supplements are not a substitute for a balanced, varied diet and a healthy lifestyle, and are not a treatment, cure, or prevention of infertility.
Expert Perspectives & Protocol Breakdown
Dr. Natalie Crawford (Reproductive Endocrinologist, USA)
What she recommends: Dr. Natalie Crawford, a reproductive endocrinologist, mentions in her patient guide a dosage of 400 to 600 mg daily to support egg quality and refers to IVF studies in which Q10 showed more mature eggs, better embryo quality, and more genetically normal embryos. She explains the mechanism via mitochondrial function ("poor mitochondrial function means more DNA errors") and at the same time expressly emphasizes the interaction with blood thinners like warfarin, as well as the fact that supplementation is "not a magic pill," but remains part of a more comprehensive approach.
→ Source: Dr. Natalie Crawford, MD – CoQ10: Does it Help Fertility?
Dr. Senai Aksoy (IVF Specialist, Istanbul)
What he clarifies: Dr. Senai Aksoy, who has been active in fertility treatment since 1998, explicitly describes the 200–600 mg daily for one to three months used in studies as "research regimens, not a proven prescription." He explicitly points out that live birth in the most cited study (Xu et al. 2018) was "only a secondary endpoint" and the difference was not statistically significant. A central warning: A planned treatment should not be postponed just to "fully" complete a Q10 course—there is no evidence that it increases the chance of a live birth.
→ Source: Dr. Senai Aksoy – CoQ10, Melatonin and NAC for Oocyte Quality in IVF
AUA/ASRM Practice Committee (USA)
What the guideline says: The joint guideline from the American Urological Association and the American Society for Reproductive Medicine on male infertility advises physicians to inform patients that "the benefit of dietary supplements (e.g., antioxidants, vitamins) in the treatment of male infertility is of questionable clinical value" – classified as a "Conditional Recommendation" with evidence grade B. It states that there are no "clear, reliable data" to support the use of the multitude of available preparations; they are "probably not harmful," but there is also no clear evidence of their effectiveness.
→ Source: AUA/ASRM Guideline: Diagnosis and Treatment of Infertility in Men, Part II
Federal Institute for Risk Assessment – BfR (Germany)
What the BfR classifies: In its statement on Coenzyme Q10, the German Federal Institute for Risk Assessment (BfR) primarily evaluates the safety aspect: In studies, occasional adverse effects such as nausea, heartburn, gastrointestinal discomfort, or diarrhea were observed at doses of up to 300 mg daily; in Germany, a daily intake of up to 100 mg is considered safe without a special warning. Above this amount, the BfR expressly recommends consulting a physician if taking blood pressure or blood-thinning medications, and advises particular caution or prior medical consultation for pregnant women, nursing mothers, and adolescents.
→ Source: BfR – Coenzyme Q10: What is known about health risks – and what is not?
Where They Differ
Dr. Crawford and Dr. Aksoy are both clinical reproductive medicine specialists, yet they draw different conclusions from the same body of evidence: Crawford’s language is more optimistic and provides a specific target dose, whereas Aksoy places greater emphasis on the lack of significance regarding live births and actively warns against delaying treatments due to Q10. The AUA/ASRM guideline contrasts these individual expert opinions with a generally more cautious, institutional assessment ("questionable clinical benefit"), while the BfR focuses primarily on safety and dosage aspects without providing an efficacy recommendation.
What the Evidence Says
The available RCT and meta-analysis data most strongly support a cautiously positive assessment for intermediate steps—more mature oocytes, fewer cancelled cycles, improved sperm parameters, higher clinical pregnancy rates—while there remains a consistent lack of evidence for an effect on live birth rates. This is most consistent with the position of Dr. Aksoy and the AUA/ASRM guideline: a plausible approach that is proven in some areas but whose overall clinical effect remains uncertain—not a proven path to more babies.
Frequently Asked Questions about Coenzyme Q10 and Fertility
Does Coenzyme Q10 really help with fertility?
In women with diminished ovarian reserve, studies have shown that Q10 improves intermediate steps such as cycle cancellation rates and embryo availability, as well as clinical pregnancy rates in a meta-analysis. According to current data, there is no statistically proven effect on live birth rates.
How much Q10 should one take for fertility?
The cited studies mostly used 200–600 mg daily for one to three months prior to planned treatment. There is no uniform, officially established dosage; in Germany, an amount of up to 100 mg/day is considered safe without a special warning.
Ubiquinone or Ubiquinol – what is the difference?
Ubiquinone is the oxidized form and ubiquinol is the reduced, biologically active form of Coenzyme Q10. Healthy adults can efficiently convert ubiquinone into ubiquinol; there is no proven advantage in efficacy for one form over the other in fertility studies.
How long before fertility treatment should one take Q10?
Studies generally used a lead time of one to three months, based on the oocyte maturation cycle. However, there is no evidence to suggest that a planned treatment should be postponed for this reason.
Is Coenzyme Q10 safe during pregnancy?
According to the BfR, there is insufficient safety data for pregnant and nursing women; higher doses should only be taken in these situations after consultation with a physician.
Does Q10 also help with male infertility?
A 2025 meta-analysis shows improved sperm concentration and motility with Q10 in men with unexplained subfertility. Nevertheless, the AUA/ASRM guideline evaluates nutritional supplementation in male infertility as being of overall questionable clinical utility.
What are the side effects and interactions of Coenzyme Q10?
Usually mild: nausea, heartburn, gastrointestinal discomfort, rarely skin rashes. Of primary concern is a potential interaction with blood thinners (e.g., warfarin/phenprocoumon) and blood pressure medications—medical consultation is important before starting use.
What does a Q10 deficiency look like – are there typical symptoms?
An isolated, clearly defined "Q10 deficiency" with specific symptoms is not clearly characterized in healthy adults; the body's own levels decline physiologically with age. Fatigue or reduced physical stamina can have many causes and should be evaluated by a physician rather than managed independently.
References & Scientific Citations
- American Society for Reproductive Medicine – Age and Fertility (Patient Education Booklet)
- Ben-Meir A, et al. Coenzyme Q10 restores oocyte mitochondrial function and fertility during reproductive aging. Aging Cell. 2015;14(5):887–895.
- Xu Y, et al. Pretreatment with coenzyme Q10 improves ovarian response and embryo quality in low-prognosis young women with decreased ovarian reserve: a randomized controlled trial. Reprod Biol Endocrinol. 2018;16:29.
- Florou P, et al. Does coenzyme Q10 supplementation improve fertility outcomes in women undergoing assisted reproductive technology procedures? A systematic review and meta-analysis. J Assist Reprod Genet. 2020;37(10):2377–2387.
- Efficacy and Safety of Coenzyme Q10 in Idiopathic Male Infertility: A Systematic Review and Meta-Analysis of Randomized Trials. World J Mens Health. 2025.
- AUA/ASRM Guideline: Diagnosis and Treatment of Infertility in Men, Part II
- WHO laboratory manual for the examination and processing of human semen, 6th edition (2021)
- NCCIH – Coenzyme Q10
- BfR – Coenzyme Q10: What is known about health risks – and what is not?
- Dr. Natalie Crawford, MD – CoQ10: Does it Help Fertility?
- Dr. Senai Aksoy – CoQ10, Melatonin and NAC for Oocyte Quality in IVF
Source Transparency: The mentioned physicians and institutions are used as sources of perspective and are editorialized independently of the scientific analysis. Clinical statements regarding diagnostics, safety, and dosage are primarily based on the cited RCTs, meta-analyses, the AUA/ASRM guideline, and the BfR statement. VEYT does not provide recommendations for individual experts or their products through this mention, and this article does not constitute fertility treatment, diagnosis, or therapy.
