Hi @Nikkilee, I haven't tried Biotin but you jogged my memory and whilst my nails didn't suffer too badly with Taxol, when I was going through menopause before BC my hair and nails went weak and brittle so I tried silica tissue salts from Martin and Pleasance. Not a vitamin but a mineral used by homeopaths and not expensive.You can read about them here. Just check with your doc.
http://schuesslertissuesalts.com.au/product/silica-schuessler-tissue-salts/On re reading I notice they're good for anxiety and insomnia too , might have to grab me some more :D