CoQ10: what the research does and doesn't show

The evidence doesn't support CoQ10 as a treatment for any condition, and it doesn't give a dose for fertility, pregnancy or any other goal. What exists is mixed: small trials, pooled doses, and results that conflict. This page covers what was tested, at what dose and in whom, and points to the full reviews.

What the evidence doesn't support

It doesn't support CoQ10 as a fertility treatment for women or men. It doesn't tell anyone whether to take it, or stop taking it, during pregnancy or breastfeeding: none of the sources we read assessed that, and we give no use guidance for either. It doesn't support a fertility dose: the 100 to 800 mg figures that appear in searches are not backed by what we read: the abstracts state 100 mg and 300 mg for men and no dose for women. It doesn't show that CoQ10 causes weight gain, headaches, constipation, diarrhoea, bloating or joint pain, and it doesn't show it relieves joint or muscle pain. Where a question has a full review, we link it.

What the trials found

Fertility in women. A 2020 meta-analysis of five randomised trials (449 women having assisted reproduction) found clinical pregnancy in 28.8% on CoQ10 versus 14.1%, with no significant difference in live births or miscarriage (Florou 2020). A Cochrane review of 63 trials (7,760 women) grouped CoQ10 with many other antioxidants, rated the evidence low to very low quality, and noted that seven included studies have since been retracted (Showell 2020). See CoQ10 for women.

Fertility in men. Three trials (296 infertile men) found better sperm concentration and motility and no increase in pregnancy rates (Lafuente 2013); a 2025 analysis of nine trials (781 men) found higher clinical pregnancy odds with a very wide interval (Bakri 2025). One 60-man trial of 100 mg a day for 12 weeks found better sperm shape but no significant change in testosterone (Gharakhani Bahar 2023). See CoQ10 for men.

Safety and stomach effects. A 2006 risk assessment by an industry trade body found stomach effects no more common at 1,200 mg a day than at 60 mg (Hathcock 2006). A 2022 analysis of 13 trials reported one gastrointestinal event among 602 people given CoQ10 (Tsai 2022). A Cochrane review of 20 antioxidants in men found more mild stomach discomfort with antioxidants overall (odds ratio 2.70, low certainty), without separating out CoQ10 (de Ligny 2022).

Weight. Two meta-analyses (17 and 20 trials) found no significant change in body weight or BMI (Saboori 2019, Ghavami 2020). See CoQ10 and weight loss.

Muscle symptoms with statins. Eight placebo-controlled trials in 472 people taking statins with muscle symptoms found no significant change in creatine kinase or muscle pain with CoQ10 (Wei 2022). That is the studied population, not advice about any medicine.

Migraine. A 42-person trial at 300 mg a day found fewer attacks than placebo (Sandor 2005); a pooled analysis of six trials found no significant change in severity (Sazali 2021). See CoQ10 and migraine.

Questions people ask

Is CoQ10 safe during pregnancy, and can you take it while pregnant?

We can't say. None of the sources we read assessed CoQ10 use during pregnancy, and we give no use guidance for it. If you are pregnant or may be, ask your doctor before taking any supplement, including whether to continue one you already take.

Can you take CoQ10 while breastfeeding, and is it safe?

Same answer: we found no source that assessed it, and we give no use guidance. Ask your doctor.

Does CoQ10 help with fertility, help you get pregnant, or help with pregnancy?

The trial results are above, and they are mixed. In women, more clinical pregnancies but no significant live-birth difference; in men, better sperm measures but conflicting pregnancy results. A supplement is not a fertility treatment. A couple trying to conceive for a year should see a clinician.

How much CoQ10 for fertility, and when to take it, start or stop?

There is no established dose or schedule, and we give no use guidance for fertility or pregnancy. The one abstract we read that states a fertility dose was in men: 100 mg a day for 12 weeks. We found no source for 400, 500, 600 or 800 mg in women, and no trial of timing. Which form is best for fertility is unknown; no trial we read compared forms.

Can CoQ10 cause diarrhoea, constipation or bloating?

The sources we read describe stomach effects as no more common at higher doses than low ones, and none quantified diarrhoea, constipation or bloating separately. If a supplement upsets your stomach, stop and ask a pharmacist; see CoQ10 side effects.

Can CoQ10 cause headaches, and does it help with headaches?

None of the safety sources we read reported headache as a side effect. In migraine, small trials found fewer attacks than placebo, with the limits in the migraine review. Frequent headaches need a clinician.

Can CoQ10 cause or make you gain weight?

Two pooled analyses found no significant change in weight, with intervals spanning a small loss and a small gain. See CoQ10 and weight loss.

Does CoQ10 help joint pain or muscle pain, and can it cause joint pain?

We found no trial of CoQ10 for joint pain and no report of joint pain as a side effect in our sources. For muscle pain in people taking statins, the pooled placebo-controlled trials found no significant change. Persistent pain needs a cause found by a clinician.

When to talk to a doctor

CoQ10 is not a treatment for infertility, headaches, muscle or joint pain, or any other condition. If you are pregnant, breastfeeding, trying to conceive, under 18, or take prescription medicine (especially a blood thinner), ask your doctor or pharmacist before taking it. See a clinician for pain that persists, headaches that are new or severe, or a year of trying to conceive without success.

Related reading: what is CoQ10, CoQ10 benefits: what the research does and doesn't show, CoQ10 dosage, CoQ10 and medications, who should not take CoQ10.