That headline is partly useful, but often exaggerated for clicks. There are things that really shouldn’t go in a dishwasher because of heat, strong detergents, and water pressure, which can damage them or create safety issues.
Here are 8 items you generally should avoid putting in a dishwasher—and why:
1. Wooden utensils and cutting boards
- Hot water and steam can cause warping, cracking, and splitting
- Wood can also lose its protective oils and roughen over time
2. Cast iron cookware
- Dishwasher strips seasoning layer
- Leads to rust and loss of non-stick properties
3. Non-stick pans (low-quality or damaged coating)
- High heat and detergent can degrade coating
- May shorten lifespan significantly
4. Sharp knives
- Blades can dull quickly from banging around
- Handles (especially wood) may weaken
5. Insulated travel mugs and bottles
- Can damage vacuum seal insulation
- Heat may reduce their ability to keep drinks hot/cold
6. Crystal or delicate glassware
- High heat can cause clouding or cracking
- Thin glass may break under water pressure
7. Aluminum cookware
- Can discolor or oxidize, leaving dull or stained surfaces
8. Copper items
- Dishwasher detergents can tarnish and damage finish
