Costco's vitamin is really powerful. Recently, with the hot weather and staying up late, my immune system has weakened a bit, and I've developed several mouth sores—both red and white ones. Eating and drinking caused sharp pain.

I asked Grok about it, bought it, and took three pills over three days. It's basically healed now.

Highly recommend!!! Especially for friends with weak immunity who are prone to mouth sores.