Do your homework when buying a memory foam mattress topper. Be sure you’re buying a topper that is actually made of memory foam, not just an egg crate topper. Also, check with the foam is made of. Some are made of fibers that can aggravate allergies. As with anything else there’s better made toppers which cost more money. Read, research and check with your doctor or chiropractor to see what is recommended.
You may want to use a topper instead of a memory foam mattress though as some toppers are made specifically to allow air flow so it doesn’t trap your body’s heat as some memory foam mattresses do. This may be the way to make a decision if you want to purchase a memory foam mattress also. If you have back pain or other chronic pain you may not want to put a lot of money into buying a mattress until you’re sure you’ll be comfortable. Giving the topper a try may be your best route.