Using the right amount of a skin care product is as important as picking the right product(s). If you don't apply enough of the product or for a too short duration, you will not get the optimal result. This is particularly crucial when using sunscreen to reach the sufficient SPF level and protection. According to a study published in the Journal of the American Academy of Dermatology by Andreas Storm MD et al. 95% of patients with a topical treatment under-dose, hence do not use enough cream.

​If there is a specific user manual mentioning the dosage, or you got a prescription, follow their recommended instructions. If the product came without specific dosage instructions, there is a general rule of thumb. The recommended amount of product to apply varies, depending on the product type.

THE 2 FINGERS RULE FOR SUNSCREEN
For sunscreen you need 1/2 teaspoon for the face or enough to cover the bottom of a shot glass and a full shot glass for the body, which should add up to 2mg per cm2. Another method is using the "rule of nines, which is used for burns. The body areas are divided into 11 area's, each representing 9% of the total. Sunscreen can be applied to each of these areas at a dose of 2 mg/cm2 (regardless phototype) if two strips of sunscreen are squeezed out on to both the index and middle fingers from the palmar crease to the fingertips, thus 2 fingers. (1)
The body areas are:
1 Head, neck, and face
2 Left arm
3 Right arm
4 Upper back
5 Lower back
6 Upper front torso
7 Lower front torso
8 Left upper leg and thigh
9 Right upper leg and thigh
10 Left lower leg and foot
11 Right lower leg and foot

FINGERTIP UNITS
For the use of other topical products there is a guidance created called Finger Tip Units or FTU's by CC Long and AY Finlay. It is a way of measuring the amount of product squeezed out of a tube with a 5mm diameter nozzle and applied from the distal skin-crease (the crease closed to the fingertip) to the tip of the index finger.

The FTU concept has been used as a central part of an education programme for parents of children with atopic eczema, has been advocated to reduce the variation in usage of topical steroids and to encourage adherence to therapy. For a serum, you may need less as they are lightweight products which should be fully "absorbed" without residue. If the skin still feels sticky after 1 minute, you probably applied too much product. A guidance would be a pea size dot on forehead, right cheek, and left cheek, which is similar to the recommended amount of retinoids (Vitamin A). However, unlike Vitamin A, using too much serum usually isn't harmful for the skin, but increases the risk of "pilling".

The precise number of FTU's required:

• face 1
• front neck and décolletage 1
• back neck 0.5
• face and neck (front and back) 2.5 
• front of trunk 6.7
• back of trunk 6.8 
• arm and forearm 3.3 
• hand 1.2 
• leg and thigh 5.8 
• foot 1.8 
• entire body 40 units

One FTU covers 286 cm2, more specifically in males and 312 cm2 in females 257 cm2. 

The quantity of cream in a fingertip unit varies:
Adult male: 1 fingertip unit provides 0.5 g
Adult female: 1 fingertip unit provides 0.4 g
.
Keep in mind this is a general guideline and the amount of product needed or results may vary also depending on skin type, concerns and the products particular attributes.

​Take care (in the right amount and duration)

​
References:
1. BMJ. 2002 Jun 22; 324(7352): 1526.Simple dosage guide for suncreams will help users Steve Taylor et al.
Illustration Tinea incognito with unjustified use of potent Topical Corticosteroids: a case series July 2017 International Journal of Basic & Clinical Pharmacology 6(8):2087 Haiya Sheth et al.

We all learned that sleeping in make-up is the ultimate skincare sin. What is bad about it is when you go 24 hours without washing your face and end up going to bed leaving your day-time make-up on. Over the course of the day, our skin accumulates pollutants, dirt and dead skin-cells.

If dirt and pollutants are left on the skin, they may cause micro-inflammation and contribute to premature ageing skin via a process called inflamm-aging and free-radical damage which is a major contributor to skin-ageing. The combination of both micro-inflammation and free-radical damage is called ox-inflammation. We should aim to reduce or preferably avoid it. Pollution, dirt and sebum (oils) can impact the skin's healthy pH balance and thus lead to a weakening of the skin barrier function, more sensitive skin, dehydration, slowed down skin-cell renewal process and thus ageing. Not removing dead skin cells together with dirt increases the risk of clogged pores. 

Make-up itself usually doesn’t contain harming ingredients. Coloured micro-pigments actually provide additional sun-protection. Make-up or foundation itself is thus not the problem, however the fact that we don’t cleanse our skin after a busy day and/or evening is what could make us age faster. Not doing your PM cleanse and care routine is anyway a missed opportunity to support your skin’s night-time recovery with beneficial active ingredients.

If you go out in the evening, take the opportunity to cleanse before getting ready and get rid of debris which was accumulated during day-time.

Don’t worry about falling asleep in your make-up once or twice. Just don’t make it a habit. I would always aim to remove eye make-up. Sleeping in full eye make-up (mascara, liner, eyeshadow) increases the risk of an eye-inflammation, redness and corneal abrasions. Waking up with “panda-eyes” filled with black rheum or goop isn’t pretty either.

Take care

One of the frequently asked questions is, if it's necessary or if there is a benefit using a special eye care or cleansing products. Yes, there is!

As I mention in many of my previous posts, the right pH-level is very important for healthy skin. Skin usually prefers a pH of around 5. However there are some area's where the skin's natural pH balance is a little bit different. One of those area's is the area around the eyes. The preferred pH-level there is around 7, thus less acidic and more alkalic in comparison to your regular cleansing or care product for face or body.

This is one of the most important reasons why I would recommend to use a special eye make-up remover and eye care product, as they are adjusted to the pH level most suitable for use in the eye area. Furthermore, special eye products are tested and proven to be safe when used around the eyes, while it isn't always recommended or proven for a regular face product. 

Some care products have a tendency to "travel" or migrate into the eye area. Even when not directly applied around the eyes, they might end up there. A special eye care product can form a "barrier" and thus help to prevent that unwanted products move to the eye area and cause irritation. I would particularly recommend the use of an eye cream when using other products containing gold standard anti-ageing active ingredients like Vitamin A, C (or derivatives of both), Hydroxy Acids (Alpha, Beta or Poly), when you have experienced some sensitivity of the eyes or eye area in the past or have a more problematic skin type.

Eye care products preferably should not contain Vitamin C (L-Asorbic Acid or related) as it requires a low pH value of <4 to be active and do it's job properly. Eye care products with Vitamin C therewith are either too acidic to be used in the eye area or alternatively too alkalic for the Vitamin C to be effective. Safe to use in the eye area are products containing Hyaluronic Acid. Although  "Acid" is in the name, Hyaluronic Acid isn't acidic. One of it's key functions is attract and bind water, which usually has a pH of ~7.

Take care!

Safe use of cosmetics and care products is particularly important for the sensitive eye area. If you've ever or never had a problem, here is how you can avoid them.. 

Irritation
If any eye cosmetic or care product causes irritation, stop using it immediately. If irritation persists, see a health care provider.

Infection
Avoid using eye cosmetics if you have an eye infection or the skin around the eye is inflamed. Wait until the area is healed. Discard any eye cosmetics you were using when you got the infection. Be aware that there are bacteria on your hands that, if placed in the eye, could cause infections. 

Hygiene
Wash your hands before applying eye cosmetics. Make sure that any instrument you place in the eye area is clean. Don't share your cosmetics. Another person's microflora may be hazardous for you.

Packaging
Don't allow cosmetics to become covered with dust or contaminated with dirt or soil. Keep containers and nozzles clean. Don't use old containers or eye cosmetics and don't re-use containers. Never trust a product that smells funky, looks dirty, or past the open-jar time.

Mascara
Discard dried-up mascara. Don't add saliva or water to moisten it. The bacteria from your mouth may grow in the mascara and cause infection. Adding water may introduce bacteria and will dilute the preservative that is intended to protect against microbial growth. Manufacturers usually recommend discarding mascara two to four months after purchase.

Storage
Don't store cosmetics at temperatures above 85 degrees F or 30 degrees Celsius. Cosmetics held for long periods in hot cars, for example, are more susceptible to deterioration and bacteria. Some products are best stored in the refrigerator. Read the leaflet or follow the instructions how to best store the product.

Application
When applying or removing eye cosmetics, be careful not to scratch the eyeball or other sensitive area. Never apply or remove eye cosmetics in a moving vehicle. Don't use any cosmetics near your eyes unless they are intended specifically for that use. For instance, don't use a lip liner as an eye liner. You may be exposing your eyes to contamination from your mouth, or to color additives that are not approved for use in the area of the eye. Avoid color additives that are not approved for use in the area of the eye, such as "permanent" eyelash tints and kohl. 

Tools
​If you use make-up brushes or sponges, clean them every week with a special product or soap. Give them additionally from time to time an extra spritz with a disinfectant.

Don't mix it up
Sometimes you might feel to mix several products or add something to the product. Problems can arise if you challenge a product’s preservative capability, which is optimal and tested only with the original formula and packaging.

Check ingredient list
As with any cosmetic product sold to consumers, eye cosmetics are required to have an ingredient declaration on the label. Check if there is anything listed you don't tolerate or like. If the product doesn't have the ingredients listed, the product may be considered misbranded and illegal. Do the same for adhesives used for lash extensions or false lashes.

Be aware of testers
Keep in mind when you come across “testers” at retail stores that they might be contaminated. If you do sample cosmetics at a store, be sure to use single-use applicators, such as clean cotton swabs. Check how the store maintains their testers. If possible, ask for a sample, especially for care products. Using a few applications gives you a better idea about the compatibility (how well your skin tolerates the product), if you like the texture and enjoy the product. 

​Take care.