It is a common misconception that tomatoes can lead to acne, most likely originating from the allergic reaction that some people have to this vegetable.
When a person has an allergic reaction to tomatoes, it often presents in the form of hives on the skin which can resemble acne, though this is definitely not the case.
So far there is no credible scientific evidence that links any food at all to causing acne. While there are certain foods which could in theory worsen acne, tomatoes are not one of them. While some people may have an allergic reaction to them, it is not the same as acne.