There is no one-size-fits-all answer to this question, as the best mattress topper for someone with fibromyalgia will vary depending on the individual's specific needs and preferences. However, there are a few things to keep in mind when choosing a mattress topper for someone with fibromyalgia. First, it is important to choose a topper that is firm but not too firm, as a too-firm topper can aggravate pain. Second, it is important to choose a topper that is made from a material that is known to be supportive and comfortable, such as memory foam. Finally, it is important to make sure that the topper is not too thick or too thin, as this can also affect comfort levels.