Alison: Nail polishes are essentially solvent-based liquid paints that dry quickly so none of them are actually non hypoallergenic. However, some do contain ingredients that are a little bit more sensitive than others. If there was a nail strengthener that I would recommend for you, it would be Nails inc
If you do have really sensitive skin and really can't get on with nail varnish at all, then bear in mind that nail strength can come from cuticle treatments. So try the OPI Perfect Partners Nail Envy and Avoplex Duo and massage it into the nail area. Buffing helps too so I recommend one of our buffing kits from Nails Inc or Leighton Denny. You can also massage in Liz Earle Superbalm on a daily basis which is 100% natural. This won't deliver instant results but it will aid nail growth and health over a period of time. A nail strengthener will paint on nail strength, while a cuticle product stimulates and works on the nail bed where the nail cells are developing.