Mascara can flake into your eyes while you sleep. You might wake up with itchy, bloodshot eyes, scratched corneas or even an infection. Make sure to remove all make up before you go to bed.

Sheer, high-gloss lipsticks offer little protection and can attract damaging UV rays to your lips. However they can be used safely. Simply apply a protective lip balm with at least SPF 30 as a base, then top with the gloss.

Nail polish, particularly darker colours, may stain your fingernails or toenails and leave them yellowed and discoloured. The stained nails will grow out, but it may take several months.  A far better option is to apply a base coat as a protective layer so that the dark colour doesn’t stain in the first place.

Cosmetics are subject to strict European safety rules,  but just because a product says it's hypoallergenic doesn't mean you won't have a reaction to it. Manufacturers will have made special efforts with the selection of ingredients and product testing to reduce the risk of adverse reactions to cosmetic products. However, no cosmetic product can be guaranteed not to cause an allergic reaction.

Because of the risk of eye infections, you may not be able to use eye makeup, including mascara, eyeliner and eye shadow, as long as you would other products. Liquid or creamy makeup can harbour bacteria more easily, so some experts recommend replacing your mascara every three months. If mascara dries out, don't add water or saliva to moisten it. That can introduce bacteria.

Cosmetic brushes, sponges, and fingertips pick up bacteria and other germs from the skin, so sharing make up can mean you're also sharing bacteria. (Moistening brushes with saliva makes this worse.) Extended exposure to light or heat can break down the preservatives that fight bacteria, so don't leave your make up in a hot car. Also, don't use cosmetics if you have an eye infection like conjunctivitis. Throw away any make up you were using when you discovered the infection.

The use of lead in cosmetic products is specifically banned by the European Union. However, lead is a naturally occurring element found everywhere in the environment, so it is possible that minute traces may be in cosmetics.  The Cosmetic, Toiletry and Perfumery Association claims: "These extremely low levels are taken into account as part of a full safety assessment to ensure their presence does not pose a risk to human health."

Kohl is a traditional type of eye makeup that can contain significant amounts of lead. Some types of eye makeup may be labelled with the term "kohl" to indicate the shade, but the product doesn’t actually contain kohl. European law requires the manufacturer or supplier of a cosmetic product is responsible for ensuring it is safe and each cosmetic must be assessed for safety by a qualified safety assessor before it is made available to the public.

All cosmetic products supplied in the UK must comply with the Cosmetics Directive which makes it illegal for anyone to supply a product that can damage human health.  The law requires that all products are assessed by a qualified safety assessor before being made available to the public. Assessments can be carried out by pharmacists, doctors, chartered biologists and chartered chemists.

Consumer Protection issues are dealt with when complaints are made to the Office of Fair Trading. When goods are sold to consumers, the goods must be safe. If the goods are unsafe and they cause death, injury or damage to property, the manufacturer, the retailer and/or anyone else in the supply chain may have to meet a claim for compensation.

Scratching the eye with a mascara wand is the most common cosmetics-related injury. It can lead to an eye infection if the scratches go untreated and infections can result in ulcers on the cornea, eyelash loss or even blindness. To avoid this type of injury, don't try to apply mascara in the car – and of course - never while driving.

"Cosmeceutical" is a popular term for a product that's meant to beautify but also treats a condition. However, robust evidence is required when making cosmetic claims. It is a breach of the Advertising Standards Agency’s code if medicinal claims are made for products that have not been granted a market authorisation by the Medicines and Healthcare products Regulatory Agency (MHRA). So a toothpaste which claims to treat sensitive teeth would be subject to the same controls as a medicine.

Lipsticks, deodorants and hair dyes have been the source of some controversy, but Cancer Research UK says the cosmetic industry is highly regulated in the UK and the EU has produced a list of banned substances that are not allowed to be used. It adds, based on available data, "there is no good scientific evidence to believe that these products could cause cancer."