"On the wagon" is a colloquial phrase that refers to someone who is abstaining from alcohol. There are various synonyms that can be used to describe this behavior. One such term is "going sober," which implies a conscious decision to avoid alcohol altogether. "Teetotaling" is another option, which suggests a permanent abstinence from alcohol. "Dry" is a more general term that indicates a period of abstinence, but it can be used to describe both temporary and permanent situations. Alternatively, one might use "sober-minded" or "temperate" to describe someone who has chosen to abstain from drinking as part of a greater effort to maintain a healthy lifestyle.