A cartridge for use with an aerosol-generating system has a housing defining a liquid containing volume. The housing includes a sidewall extending from a mouthpiece end to a power supply end. The housing includes a transparent region forming at least a portion of the sidewall. The housing includes a light source fixed to the sidewall. The light source is configured to transmit light into the liquid containing volume. The light source may be fixed to an inner surface of the sidewall, fixed to an outer surface of the sidewall, or form a portion or the sidewall.