Everyone has different senses and sensitivities, and they can change over time and circumstances. So it's a good idea to try to use high-quality, gentle, and nourishing products that minimize irritating and harsh chemicals. And it's also good for products to literally be clean-- as in not old or dirty -- because makeup can be a source of irritation or infection.

Water-based nail polishes are gentle on nails and do not have strong fumes. They may not last as long as other types of polishes, but that could be a good thing for people with fragile nails. Traditional nail varnishes can have flammable and noxious chemicals, while gel nail polishes were recently banned in the European Union due to toxicity concerns with one of their main ingredients. Water-based nail polishes are virtually odorless and do not need the same harsh chemicals to remove them as traditional varnishes, so this can also be desirable to people with sensitive skin or sensitive senses of smell.

Sensitive skin can be a result of an underlying skin condition (eczema, psoriasis, rosacea), hormone changes, environment (heat, wind, pollution), nutrition/hydration, medications, clothes, cosmetics, cleaning products, and even stress. Given the aforementioned list, many people have probably experienced skin sensitivities at one time or another. It can be hard to identify one's personal triggers, and your triggers can change. But avoiding triggers, staying hydrated, moisturizing the skin, and using gentle products are ways to try to take care of sensitive skin.