Malaria: mostly a no — with mapped exceptions
CDC recommends insect-bite precautions only — no chemoprophylaxis — for Bangkok, Chiang Mai, Chiang Rai, Koh Samui, Phuket, and reports no transmission at all in Pattaya or Krabi’s islands. Vietnam is the same story: no risk in Hanoi, Ho Chi Minh City, Da Nang, Nha Trang. The exceptions are rural border regions — Thailand’s borders with Burma, Cambodia and Malaysia carry risk, and notably both chloroquine AND mefloquine resistance, which narrows the valid prophylaxis to atovaquone-proguanil, doxycycline, or tafenoquine. Trekking those borders is a different trip than Phuket.
Travelers’ diarrhea is the actual everyday risk
Southeast Asia is the textbook case for carrying standby azithromycin specifically: CDC names it the preferred empiric treatment in the region because fluoroquinolone-resistant Campylobacter has undermined the older standby antibiotics. A single 1,000 mg dose, carried and used only if moderate-to-severe illness hits.
Dengue — the risk no pill covers
Dengue circulates year-round in both countries, and there is no preventive pill and no routinely recommended traveler vaccine — bite avoidance is the whole defense. We say this plainly because a travel-medication consult that implies a pill for everything would be lying: repellent, treated clothing, and screened rooms are the dengue plan.
What needs a clinic
Typhoid vaccination is CDC-recommended for most travelers to both countries. Routine vaccines (MMR, tetanus, flu) should simply be current. Injections are clinic items — your plan will say so where your route warrants them.
What a $49 consult typically covers here
- Azithromycin — travelers’ diarrhea standby (self-treatment)
For the mainstream trail, the plan is often refreshingly small: standby diarrhea treatment + honest counseling. Border trekking reopens the malaria conversation. Your physician composes the final plan for your exact route. Sources: CDC destination pages + Yellow Book 2026.