Peter Thomas Roth Retinol Fusion PM Night Serum

You'll also recognize water as that liquid we all need to stay alive. If you see this, drink a glass of water. Remember to stay hydrated!

It has the most scientific studies backing up its skin benefits out of all the non-prescription ingredients.

Retinol is proven to:

This is why retinol is effective at removing wrinkles, fading dark spots, treating acne, and reducing the appearance of pores.

Studies show retinol is less effective when exposed to UV. Be sure to look for appropriate packaging to keep your retinol potent (similar to Vitamin C).

Using retinol or any retinoids will increase sun-sensitivity in the first few months. Though studies show retinoids increase your skin's natural SPF with continuous use, it is best to always wear sunscreen and sun-protection.

We recommend speaking with a medical professional about using this ingredient during pregnancy.

Retinol may cause irritation in some people, so be sure to patch test. Experts recommend 'ramping up' retinol use: start using this ingredient once a week and work up to using it daily.

Read about Tretinoin

Tocopheryl Acetate is commonly found in both skincare and dietary supplements.

As you may know, regular vitamin C is notorious for breaking down when exposed to sunlight and air. Ascorbyl Palmitate is more stable and degrades at a slower rate.

Research on whether it converts efficiently into active vitamin C once it's applied on your skin is still limited.

Some in-vitro studies suggest it may support collagen production, but it is not considered one of the stronger vitamin C derivatives, like:

Due to the palmitic acid base, this ingredient may not be fungal acne safe. Comedogenic studies have also shown this ingredient to have a rating of 2.

It's also worth keeping in mind that comedogenic and irritancy ratings are tested on individual ingredients, not finished formulas. The final product's formulation, concentration, and other ingredients all play a role in how something actually behaves on your skin.

A clinical study found that applying 0.5% bisabolol daily for 8 weeks produced an average 9% decrease in skin pigmentation. Researchers found it can also suppress the process that leads to excess melanin production in skin.

In vitro studies found that bisabolol combined with propylene glycol significantly increased skin permeability by increasing lipid fluidity in the stratum corneum.

You'll likely see use concentrations quite low, usually 0.1-0.2%.

Overall, this is a well-tolerated ingredient that works well in formulas designed for sensitive, reactive, or post-procedure skin.

It plays well with most ingredients and is typically used at 0.1-1%. However, concentrations up to 50% have been reported in moisturizers.

Depending on the source of this ingredient, lecithin may not be fungal acne safe. This is because some sources of lecithin come from soybean oil, which may feed the malassezia yeast that causes fungal acne.

We recommend reaching out to the brand you are purchasing from to inquire about the source of their lecithin.

This ingredient is used in medicine to help treat low blood levels of phosphorus.

This property also makes Pentylene Glycol a great texture enhancer. It can also help thicken or stabilize a product.

Pentylene Glycol also acts as a mild preservative and helps to keep a product microbe-free.

Some people may experience mild eye and skin irritation from Pentylene Glycol. We always recommend speaking with a professional about using this ingredient in your routine.

Pentylene Glycol has a low molecular weight and is part of the 1,2-glycol family.

The common safety discussion around this ingredient involves a manufacturing byproduct called 1,4-dioxane.

Trace amounts can form during production but the EU's Scientific Committee on Consumer Safety has concluded that levels at/below 10 ppm in finished products are safe (commercial products consistently fall within acceptable margins).

True allergic reactions are uncommon and the CIR Expert Panel has confirmed this ingredient to be safe as used in cosmetics.

Because it is derived from lauric acid, it may not be fungal acne safe.

Is it bad for your skin?

The answer comes down to concentration. Patch and wash studies have found highly concentrated alcohol-based hand rubs (60-100%) cause less barrier disruption than washing with a basic detergent like SLS. The only measurable effect in these studies was a temporary dip in skin hydration.

Concentrations below 12-15% in leave-on cosmetics is generally well-tolerated. Concentrations above start to see increased transepidermal water loss (TEWL) and reduced hydration.

In concentrations about 58%, it creates temporary channels in your skin's lipid layers to become more permeable and allow other ingredients to slip through easily.

This ingredient can be up to 80% of the formula in alcohol-based perfumes.

Overall, this ingredient is probably harmless if found lower down an ingredients list but worth side-eyeing if it's high up (especially if your barrier is already struggling).

Alcohol can worsen dry skin, eczema, and oily skin, especially at higher concentrations. This is because it can increase transepidermal water loss and decrease hydration to disrupt the skin barrier.

According to the National Rosacea Society based in the US, you should be mindful of products with these alcohols in the top half of ingredients.

True allergic contact dermatitis to ethanol is uncommon, but be sure to patch test if you have dry or sensitive skin.