sex toys and allergies
People who live with MCS and reduced immune systems usually know just how to shop and take care of their needs. The most important consideration is knowing what is really in what you are using. Be very careful with store claims about products being "all natural" or other claims. More often than not the store people don't know what this means, and in some cases they offer innacurate information about products out of their own ignorance (or a desire to sell you something more expensive).
Unfortunately when it comes to rubber and elastomer sex toys, in almost all cases we don't know what they are made of. There has never been any clinical study of plain rubber sex toys and the manufacturers are not willing to disclose what is in their products - fortunately many of the sex toys we carry are made of silicone and other non-porous materials. If you the cheapest way to explore with sex toys is to use a condom on any porous sex toy you try.
Latex allergy is fairly common and latex is found in most condoms and gloves, and many dildos, vibrators, and sensation toys. Never assume a toy is latex free. While a lot of mass manufactured dildos are not made from latex, they are often poured into moulds that have come into contact with latex, in factories where latex is being used. Usually the one exception to this is silicone dildos. Most small silicone manufacturers only work with silicone and thus can guarantee that there will be no latex or phthalates in their products. It is still worth asking if you have an allergy.
If you have a latex allergy, there are alternatives for both toys and safer sex gear. There are now polyisoprene non-latex condoms and condoms on the market, as well as non-latex nitrile gloves and polyurethane dams. All these products are made from polyurethane, nitrile, or polyisoprene and while they come with their own limitations they offer options for people with severe latex allergies.
Unfortunately some toys designed for penetration (whether they vibrate or not) are being made with a scented rubber. Manufacturers are doing this to hide the unpleasant smell of the less expensive rubbers they use. But the scent is sometime strong and can induce a reaction. Again, when buying toys, it's best to ask if the toy is scented. If the person doesn't know, insist on being able to open the package and smell the toy before you buy it. Also, some people will react to the dyes in toys for penetration. The easiest way to deal with all these concerns is to use condoms on all your sex toys or use a sex toy made of a non-porous material like silicone, stainless steel or glass.
If you want more information on this topic a great place to start your search is Immune Web. It's a website for people with fibromyalgia, chronic fatigue syndrome, multiple chemical sensitivities and more.