Mattress topper for very firm mattress

[SilverSixpence]

DH insisted on getting an orthopaedic extra firm mattress but I'm finding it too hard. Would a mattress topper make it more comfortable and if so which type?

I have dust allergies so might be best to avoid the down ones, although they do sound nice.

We bought a memory foam topper (with its own cotton zip round cover) and it made our already comfy mattress just heaven! Dh bought it (he's asleep so can't ask where from or price and I can't remember at the mo). Dh is v thrifty so it won't have been v ££££. My brother bought a ££££ tempur mattress and he and my sil hated it. He's a tall, muscle bound man and apparently would feel like he was sat in a bucket each night because it dipped in a v shape when he was in it and sil rolled into him.