Swallowing heroin would be very simular to swallowing any strong opiate. Euphoria, sluggishness, pinpoint pupils, sweating, nausea, hyperactivity, constipation, sweating, etc. etc. If you are thinking of swallowing heroin, as opposed to smoking or injecting, then you are still susceptible to all of the addictive properties. Swallowing is no less addictive than other routes of administration.