Pharmaresearch Rejuvenex Cream

You'll likely see it paired with methylparaben to cover the full range (including gram-negative bacteria).

This ingredient is effective at low concentrations (~0.2-0.5%) and stable across a wide pH range (4.5-7.5 pH). It's effectiveness drops off above pH 8 and it can lose potency when combined with non-ionic surfactants like polysorbate 80 due to micellization.

The regulatory bodies have concluded this ingredient to be safe as used in cosmetics. The EU has capped it at 0.14% and combined parabens are not to exceed 0.8%.

While parabens do cross the stratum corneum, only about 1% remains for absorption into the body. This is because most of it is metabolized within living skin.

It plays several roles in a formula:

Typical use levels for this ingredient sit around 1-10% and the Cosmetic Ingredient Review Expert Panel has affirmed safety at concentrations up to 25% in leave-on products.

Multiple assessments have found it to be non-irritating and non-sensitizing to most people.

However, there have been some cases of allergic contact dermatitis in patients with chronically compromised skin barriers.

Cetearyl alcohol has a comedogenic rating of 2 and irritancy rating of 1. Both of these numbers come from the 1989 study that used rabbit ears; a "2" means mildly comedogenic and a "1" means low irritancy.

Here's the catch: rabbit skin is more sensitive than human skin and throws a lot of false positives. A 1996 reappraisal found that ingredients rated 1-2 in the rabbit ear tests are generally safe for humans.

Remember comedogenic ratings are unable to assess the entire formula of a product or how it will react on your skin. Just be sure to patch test if you are unsure about certain ingredients.

This ingredient is not fungal acne safe. Cetearyl alcohol is a fatty alcohol with chain lengths that fall within the range that Malassezia can metabolize.

A 2019 study has also observed Malassezia growth in the presence of this ingredient, confirming it to be not-fungal acne safe.

Reported use levels range from 0.1% or less to over 50% depending on the product type.

Irritation and allergy risk is also low: undiluted single applications caused little or no irritation in rabbit skin and eye tests, it was not a sensitizer in guinea pigs at 15%, and repeat insult patch tests at 1-5% showed no sensitization.

This ingredient does have a comedogenic rating of 3 from Fulton's rabbit ear assay. Keep in mind that rabbit ear models tend to overstate what happens on human skin and finished products behave differently than raw ingredients.

As for fungal acne, this ingredient has supposed the growth of Malassezia furfur and sympodialis (but not M. globosa or M. restricta) in direct testing.

On the other hand, lanolin is able to reduce transepidermal water loss (TEWL) by about 20-30%. It can also incorporate into the lipid matrix to surround skin cells and reinforce the skin barrier.

This is why you'll see lanolin as an ingredient for heavy-duty moisturizers.

You might have seen an "allergy concern" that gives lanolin a bad reputation. The rate of lanolin contact allergy in the general population is estimated to be under 0.5%, and most of these are seen in people with compromised-skin dealing with eczema, atopic dermatitis, or leg ulcers.

Healthy, intact skin tolerates lanolin well. Even people who have previously reacted to it test negative on patch tests when the test is done on normal skin.

Because lanolin comes from an animal, it is not considered vegan. Sheep secrete lanolin through sebaceous glands to help protect their skin from the environment.

Lanolin has a reputation as pore clogging but that comes almost entirely from rabbit ear testing done decades ago (and that model has aged badly).

This ingredient does have a comedogenic rating of 0-1; the tests state this score means the ingredient has low or non-existent chance of clogging your pores.

Keep in mind that the authors of the rabbit ear test proposed that a material needs to score consistently above 3 in the rabbit assay before it means anything for real skin.

A separate review found the model has serious performance problems and no correlation with human experience. Concentration matters a lot too: in one study, Acetylated Lanolin Alcohol scored 4 to 5 at full strength but dropped to a 1 when diluted to 2.5%, and finished products containing "comedogenic" ingredients didn't raise microcomedone counts in people.

Lanolin contains esters exactly in the range that the Malassezia yeast can synthesize, making this ingredient not fungal acne safe.

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!