Lycopene: what the research does and doesn't show

The evidence doesn't support lycopene supplements as a treatment for infertility, a guaranteed-safe option during pregnancy, or a cause of digestive symptoms like constipation, diarrhea or headaches — mostly because that last group hasn't actually been studied. The one outcome with real trial data outside cancer and heart-health research is a modest, mixed effect on sperm quality measures.

What the evidence doesn't support

It doesn't support lycopene as a cause of constipation, diarrhea or headaches: our search turned up no dedicated human trial testing isolated lycopene supplements against any of those specific symptoms, in either direction. It doesn't support lycopene as a treatment for male infertility — the trial evidence that exists is limited to a few sperm-quality measures, not a clinical infertility outcome like pregnancy rate. And it doesn't support a claim that lycopene supplementation is established as safe during pregnancy; we found no dose-matched safety trial in pregnant people, which is a reason for caution rather than reassurance.

What the trials found

The best-tested outcome here is male fertility. A 2025 systematic review and meta-analysis pooled 4 clinical studies covering 151 men, looking at whether lycopene supplementation changed several semen parameters. It found a statistically significant improvement in sperm concentration and in one measure called nonprogressive motility (sperm that moves but not in a forward, purposeful pattern). It found no significant effect on total motility, progressive motility (forward-moving sperm, generally considered the more clinically relevant measure), sperm morphology, semen volume, or sperm DNA damage. The authors themselves described the evidence as showing "modest" benefits, flagged publication bias and inconsistency across the four underlying studies, and called for larger, better-designed trials before drawing firm conclusions. This is evidence about specific lab measurements in semen, not a demonstrated effect on fertility itself, and it isn't a basis for treating infertility with lycopene.

For digestive tolerability, we didn't find a controlled human trial designed to test lycopene supplements specifically against constipation, diarrhea or headaches. The dedicated safety literature on lycopene (see lycopene side effects) documents one case report of benign, reversible skin discoloration at an extremely high dietary intake, but nothing on digestive symptoms at standard supplement doses. That's a gap in what's been formally tested, not evidence that those symptoms don't occur — an unstudied question is different from an answered one.

For pregnancy, the honest answer is that we found no dose-matched trial establishing the safety of lycopene supplementation in pregnant people. Lycopene is present in ordinary foods people eat throughout pregnancy, but that's a different question from the safety of an isolated, concentrated supplement dose, which hasn't been formally tested in this population.

Questions people ask

Can lycopene cause constipation?

We found no dedicated trial testing isolated lycopene supplements against constipation. There's no evidence either way at this point — it's an unstudied question, not a documented side effect.

Can lycopene cause diarrhea?

Same answer as constipation: no dedicated human trial has tested this specifically for lycopene supplements. See lycopene side effects for what has been documented.

Can lycopene cause headaches?

We found no trial reporting headaches as a tested or observed outcome of lycopene supplementation.

Is lycopene good for male fertility?

A 2025 meta-analysis of 4 small clinical studies (151 men) found lycopene supplementation significantly improved sperm concentration and one measure of sperm motility, with no significant effect on several other semen measures. That's a modest, partial finding in specific lab measurements — not a demonstrated effect on actual fertility outcomes, and not a basis for using lycopene to treat infertility.

Is lycopene safe during pregnancy?

We found no dose-matched human safety trial testing lycopene supplements in pregnant people. Anyone who is pregnant or nursing should talk to a doctor before adding any supplement, lycopene included.

When to talk to a doctor

Anyone dealing with persistent digestive symptoms, fertility concerns, or who is pregnant or nursing should talk to a doctor rather than rely on a supplement label. Lycopene is not a treatment for infertility or any digestive condition, and nothing in the evidence above supports using it as a substitute for medical evaluation or care.

Related reading: lycopene side effects, who should not take lycopene, and lycopene benefits: what the research does and doesn't show.