Notable beverage examples include caffeine, found naturally in tea and coffee and added to many soft drinks, hops in beer, and quinine in tonic water.
Potent bittering agents may also be added to dangerous products as aversive agents to make them foul tasting, so as to prevent accidental poisoning.
Examples including anti-freeze, household cleaning products[1] and pesticides such as slug pellets.
In general, dangerous products with bright colours, which may be appealing to children, often contain agents such as denatonium.
Prior to the introduction of hops, many other bitter herbs and flowers were used as bittering agents in beer, in a mixture called gruit, which could include dandelion, burdock root, marigold, horehound (the German name for horehound means "mountain hops"), ground ivy, and heather.