Ingredient dictionary

PEG-40 Hydrogenated Castor Oil

PEG-40 Hydrogenated Castor Oil is a water-soluble emulsifier made from castor oil. Its main job is to help oils and water blend and stay mixed. It is on the label of 58 products in our library. Checked against our library November 6, 2026.

The catch: none for most people; check the full product list if your skin reacts easily.

What PEG-40 Hydrogenated Castor Oil does

Helps oil and water stay blended
Dissolves oils and fragrance into water-based products
Supports an even, stable texture

PEG-40 Hydrogenated Castor Oil starts with castor oil from castor beans. The oil is hydrogenated, which makes it more stable, then reacted with ethylene oxide to add a water-loving chain. PEG stands for polyethylene glycol, and the 40 refers to the average number of those chain units.

Formulators use it as an emulsifier, a helper that keeps oil and water mixed, and as a solubilizer, which dissolves oils and fragrance into water-based products. That is one reason it appears in clear products. In a finished product it usually feels smooth and light on skin and hair.

Good for

Suits anyone who uses everyday rinse-off or leave-on products like body wash, shampoo, cleanser or moisturizer.

Be careful if

Nothing in particular for most skin types.

Frequently asked questions

Is PEG-40 Hydrogenated Castor Oil safe?

It is widely used in rinse-off and leave-on products and is generally well tolerated by most people. As with any cosmetic ingredient, a patch test is a sensible step if your skin is sensitive. Stop using a product if you notice redness or itching.

Is PEG-40 Hydrogenated Castor Oil the same as castor oil?

No. Castor oil is the plant oil itself. This ingredient starts from castor oil, but it is hydrogenated and then reacted with ethylene oxide, so it works mainly as a water-mixing helper, not as a rich oil.