Hi & Welcome to HCM.
I can understand your concern.
Alcohol consumption may reduce the efficacy of the anti
rabies vaccines.
Although there's no dietary restriction as long as the anti rabies vaccine is given, however it is advisable to stay away from alcohol because of the following reasons:
1. There may be unexplained interactions between efficacy of the vaccine & alcohol intake.
2. Rabies
vaccination provides immunity against rabies infection while consumption of alcohol decreases the body immunity.
3. Individuals who receive the anti rabies vaccine may experience symptoms such as headache, nausea,
dizziness, etc. which are similar to the symptoms experienced by intake of alcohol.
4. The symptoms of
alcohol intoxication can mimic the symptoms of rabies infection: confusion, agitation,
anxiety, muscle issues. It would be hard to tell if your symptoms are from the alcohol or due to rabies infection itself.
Based on the above mentioned facts, it is better your friend should avoid alcohol consumption.
Best of your health.