While choosing a mattress to address your problem of back pain you must see the mattress conformability i.e. how well the mattress adjusts to your body contours. A firm mattress provides an overall support for the body. However, an excessively firm mattress can be a reason for severe back/shoulder pain, especially for side sleepers. Soft mattress firmness can provide good comfort but it may not have enough support.
Hence a medium firm mattress is an ideal choice.
Lie on the mattress at a store for 15 minutes to see if the mattress firmness suits you.
Check the support level i.e. how effectively a mattress can support a heavier person and also how it keeps the sleeper’s body on a plane level.
Also refer to our blog on body weight, body shape and sleep positions to help you choose a good mattress for your specific need.