What non-alcoholic drinks pair well with very spicy food?

Dairy is the most effective — whole milk or lassi. Casein in the dairy binds to capsaicin and removes it from the palate more effectively than any other beverage. Mexican horchata (rice milk with cinnamon) is also surprisingly effective — the fat in the rice milk helps even though the fat content is lower than dairy. Both are traditional accompaniments to spicy food for exactly this reason.

Agua fresca — particularly hibiscus or tamarind — also works reasonably well for moderate spice. The acid and sweetness together rebalance the palate after a spicy bite without spreading the capsaicin the way plain water does. Not as effective as dairy but pleasantly complementary to the flavours in a burrito.