Staying healthy in Thailand in 2026 requires a focus on water safety, hygiene, and mosquito protection. First, never drink tap water; only use bottled or filtered water, even for brushing your teeth if you have a sensitive stomach. Most ice in tourist areas is factory-made and safe, but "crushed" ice in remote areas is riskier. When eating street food, follow the "locals" rule: eat where the crowds are high, as the food turnover is fast and fresh. Avoid "pre-peeled" fruit or salads that may have been washed in tap water. Hand hygiene is critical; carry a small bottle of high-alcohol sanitizer and use it before every meal. For tropical diseases, use a 30-50% DEET repellent to prevent Dengue and Zika, especially at dusk. While "Thai Belly" is common for a day or two as your gut acclimates to new spices and MSG, following these steps—along with being up-to-date on Hep A and Typhoid vaccines—will significantly reduce your chances of a major illness ruining your vacation.