I think it depends on how heavy you are. I am kind of long & lean not heavy and no. We have a probably 18 year old mattress and it's survived thousands of rounds of sex and nights of sleep. No mattress has caused me back pain BUT one time I did have to put a board under the mattress I had because the combination of frame (it was not a real bed frame just a space a mattress fit) and soft mattress did hurt.

But it's a purchase that will last for years, regardless. If yours is old why not get one, one that suits you perfectly? Sleep is so important to your health.

There are different types of mattresses, most of it is personal preference, except for making sure they are all full body so that no house guests accumulate inside. I personally prefer mem foam mix with some other material that makes the mattress just soft enough. As mentioned by others the mattress will not magically fix everything but it can greatly help not to make it worse.

Marshall Mattress. I prefer the tight top - it sleeps cool and you can flip it. Mine is nice and firm, but they do have softer ones.

Avocado Mattress on a Thuma bed frame. Heaven. And really fucking expensive too.

Cooling memory foam + an adjustable base is totally worth the money, but it’s also going to set you back a lot out of pocket.

We buy ours from American Furniture Warehouse because they have a 30 money back guarantee. For us we sleep on it for three weeks and if we're not in love we swap it for another one. We get a new one every 8 years pretty religiously and so far this method has done us well.

We typically get one of if not the most expensive mattresses they have.