Eating out with allergies or dietary restrictions in Phuket is manageable with some preparation, though it requires more active communication than some destinations.
Common problem ingredients
Fish sauce, shrimp paste and oyster sauce appear in many dishes that don't obviously look like seafood, which matters for shellfish allergies and for anyone avoiding seafood for other reasons. Peanuts and other nuts also appear widely, including in sauces where they're not visually obvious.
Communicating clearly
Simple, direct phrasing works best — naming the specific ingredient to avoid ("no peanuts," "no fish sauce") rather than a general category, since staff may not immediately connect "vegetarian" with needing to also exclude fish sauce, which is technically not vegetarian but easy to overlook.
Where it's easiest to eat safely
Larger hotel restaurants and international chains are generally more used to handling specific allergy requests than small street stalls, where a single vendor is cooking everything to order from a shared set of sauces and pastes.
Carrying a translation card
A written card in Thai listing your specific allergy or restriction, shown directly to kitchen staff, removes any ambiguity from a spoken conversation — worth preparing before you travel if your restriction is serious.