Hyaluronic acid is a substance that occurs naturally in the body and has many medical and commercial uses. It is available in a variety of forms, including dietary supplements, face creams, serums, eye drops, and injections. Here are some details about hyaluronic acid based on the search results:

Positive:

• Hyaluronic acid is a natural substance found in the fluids in the eyes and joints. It acts as a cushion and lubricant in the joints and other tissues.
• Taking hyaluronic acid or using cosmetic products that contain it may improve skin hydration and reduce signs of aging.

Negative:

• There are no negative details about hyaluronic acid in the search results.

Ingredients or materials:

• HDM Serum Facial Ácido Hialurónico contains Deionized Water, Propylene Glycol, Glycerin, Urea, Sodium Hyaluronate, and Polyhydroxy Acid (PHA) .
• Etienne Serum 1.5% Ácido Hialurónico contains Aqua, Glycerin, Sodium Hyaluronate, Polyacrylic Acid, and DMDM Hydantoin.
• Hyaluronic acid is a linear glycosaminoglycan (GAG), an anionic, gel-like, polymer, found in the extracellular matrix of epithelial and connective tissues of vertebrates.

It is important to note that hyaluronic acid is generally considered safe and gentle, and is not a feared-by-everyone-mostly-without-scientific-reason paraben.