I didn’t have the faintest idea

Tuna salad is a mix of canned tuna, mayo, and fresh ingredients like celery and onions—all of which spoil quickly if not stored properly.

Once opened or mixed, tuna salad becomes highly perishable. Bacteria grow rapidly between 40°F and 140°F, so it should never be left out for more than two hours.

Refrigeration slows spoilage but doesn’t stop it. Store tuna salad in an airtight container, keep it below 40°F, and eat it within 3 to 5 days.

Signs it’s gone bad include a sour smell, slimy texture, or discoloration. Ignoring these signs can lead to food poisoning with symptoms like nausea, vomiting, and cramps.

Food safety experts agree: if the salad was made with fresh ingredients, stored cold, and never left out, it’s safe up to five days—but only if handled correctly. Don’t rely on luck or personal anecdotes. Label the date, avoid double-dipping, and chill leftovers immediately. When in doubt, toss it out. It’s safer to lose a meal than risk getting sick.