Does lycopene cause diarrhea, bloating or constipation?

We found no dedicated human trial reporting on digestive tolerability specifically for isolated lycopene supplements — so there's no research directly showing lycopene causes diarrhea, bloating or constipation, but there's also no trial that specifically ruled it out. That's an evidence gap, worth stating plainly rather than treating as a clean bill of health.

What's actually been tested

The clearest documented lycopene side effect is unrelated to digestion: a benign, reversible orange-red skin discoloration, seen only after extremely high, sustained dietary intake — roughly 1 kg of a lycopene-rich fruit a day in the one case report on record, far beyond a standard supplement serving. See lycopene side effects for that case in full. Digestive tolerability at typical research doses (10-25 mg a day) hasn't been the subject of a dedicated trial that we found.

Bloating and constipation

No trial identified for this page measured bloating or constipation as an outcome for isolated lycopene. If either starts after you begin a lycopene supplement, it's more likely to come from something else in the capsule — the oil carrier, the capsule shell, or another ingredient in a combination product — than from lycopene itself, though that's a general observation, not a dose-matched finding.

Itching

We found no research linking lycopene supplements to itching. A new skin reaction after starting any supplement is worth mentioning to a doctor or pharmacist, particularly if you have a known tomato allergy and are taking a tomato-extract form of lycopene — see who should not take lycopene.

Red or discolored stool

We found no research documenting lycopene supplements changing stool color. Lycopene is a red-orange pigment, so it's not an unreasonable question, but nothing in the research we reviewed tested for it either way. If you notice a change in stool color that's unexplained or persists, that's worth checking with a doctor rather than assuming it's the supplement.

Questions people ask

Does lycopene cause diarrhea?

No dedicated trial has tested that for isolated lycopene supplements. If digestive symptoms start after you begin taking one, mention it to a doctor or pharmacist rather than assuming lycopene is or isn't the cause.

Can lycopene cause itching?

We found no research linking lycopene to itching. A new reaction after starting any supplement is worth flagging to a doctor, especially with a known tomato allergy.

Can lycopene cause red stool?

We found no research testing for this. Nothing rules it out, but nothing documents it either — an unexplained or persistent change is worth mentioning to a doctor.

Related reading: lycopene side effects, who should not take lycopene, and lycopene and medications: what to check.