Pepto bismol?? cough syrup?

The active ingredient in Pepto Bismol is Bismuth Subsalicylate.  You might try that name at your local Nhà thuốc tây. 

Anecdotally, when I was a farmer in my distant past, I used to purchase a product which was supposed to cut down on unwanted drift from sprayers.  It listed Bismuth Subsalicylate as it's active ingredient and both smelled like and had the same pink color as Pepto Bismol.  I never was tempted enough to taste it but I am pretty sure that it was the same thing and at a fraction of the drugstore price.

@Thaiger none of the Google searches had the best answer for this. It is readily available through online stores like Tiki and Lazada. I am still a little skittish about the delivery process in Vietnam as my Vietnamese is not good so I had a Vietnamese friend ship to her house.

Please note you can by gaviscon and lotto mart carries this

@Thaiger none of the Google searches had the best answer for this. It is readily available through online stores like Tiki and Lazada. I am still a little skittish about the delivery process in Vietnam as my Vietnamese is not good so I had a Vietnamese friend ship to her house.
-@Nathan Holth

You are responding to a 5 year old post, the poster hasn't been on the site for 3 years.

Please note you can by gaviscon and lotto mart carries this
-@gbride101g

  As the gentleman above mentioned, this is an ancient thread.

However a note of caution - Some medicines from India have killed a lot of people recently