Hi, guys! This is a short story about where to buy baking soda in Thailand.
I had never had the necessity to get the baking soda (sodium bicarbonate) in Thailand until my gums got sore and, as it is known, gargling mouth with baking soda dissolved in warm water is an effective treatment in such a situation. I visited three 7-eleven shops (in a small city called Prachuap) but they had no baking soda there (I used Google.Translate on my smartphone to explain to them what I needed).
One of 7-11 shop assistant recommended me to go to a Tesco Lotus. Alas, I found only a kind of expensive baking powder there. (I don't know if it is normal for Tesco... or I was just unlucky). I was disappointed and I gave up for a while.
But this is a story with the happy ending. Later in Bangkok, I found baking soda in Big C supermarket. The price was just 21 baht (a 300-gram pack).
Big C supermarkets can be found almost everywhere in Thailand e.g. in Bangkok, Phuket, Pattaya, Koh Samui, Krabi, Hua Hin, Chiang Mai etc. So this is where you can buy baking soda in Thailand.