Though this ingredient works well with most skin types, some people with sensitive skin may experience a reaction such as allergic rashes, closed comedones, or itchiness.

Tea tree may cause sensitivity and irritation for some people. This oil naturally contains fragrance such as linalool and limonene.

However, research shows irritation usually occurs when using pure tea tree oil and not in cosmetic products.

Tea tree oil was found to help relieve the symptoms of psoriasis in one study.

Tea tree oil is toxic when ingested. Another study showed it to caused damage to the nervous system of dogs and cats when applied to their skin or given orally.

D-panthenol is also known as dexpanthenol. Most cosmetics use dexpanthenol or a mixture of D and L-panthenol.

Panthenol is famous due to its ability to go deeper into the skin's layers. Using this ingredient has numerous pros (and no cons):

Like hyaluronic acid, panthenol is a humectant. Humectants are able to bind and hold large amounts of water to keep skin hydrated.

This ingredient works well for wound healing. It works by increasing tissue in the wound and helps close open wounds.

Once oxidized, panthenol converts to pantothenic acid. Panthothenic acid is found in all living cells.

This ingredient is also referred to as pro-vitamin B5.