What Is Sodium Hydroxymethylglycinate?
Sodium hydroxymethylglycinate is a salt derived from the amino acid glycine that has been reacted with formaldehyde and sodium hydroxide, giving it preservative power while keeping the molecule water-soluble. First introduced in the early 1990s as a gentler alternative to older preservatives, it quickly found a place in skin and hair care formulas looking for broad-spectrum protection against bacteria and fungi.
Commercial production starts with plant-based glycine. The glycine is combined with a small, tightly controlled amount of formaldehyde, then neutralized with sodium hydroxide. The end product is purified and dried into a fine white powder that dissolves easily in water-based products.
You will most often see sodium hydroxymethylglycinate in moisturizers, lotions, serums, shampoos, conditioners, masks and leave-on hair treatments where long shelf life and a smooth skin feel are both important.
Sodium Hydroxymethylglycinate’s Cosmetic Benefits/Uses
This ingredient offers two main perks for formulators and, in turn, for the people using the product.
- Preservative: It keeps water-based products free from bacteria, mold and yeast, helping the formula stay safe and effective for many months even when stored in a humid bathroom.
- Hair conditioning: It has a mild smoothing effect on the hair shaft so shampoos and conditioners can leave strands softer and easier to comb without heavy buildup.
Who Can Use Sodium Hydroxymethylglycinate
Products preserved with sodium hydroxymethylglycinate are generally suitable for oily, dry, combination and normal skin because the ingredient itself is used at very low levels and does not clog pores or add extra oil. People with highly sensitive skin or a known allergy to formaldehyde may prefer to skip it since the molecule can release trace amounts of that compound over time.
The raw material is manufactured from plant sourced glycine and involves no animal derived inputs, making it appropriate for vegans and vegetarians.
No specific warnings exist for pregnant or breastfeeding women when the ingredient is used as directed in cosmetics. This is not medical advice and anyone who is expecting or nursing should check with a healthcare professional before starting a new product just to be safe.
The preservative does not make skin more prone to sunburn so it is not considered photosensitizing. It is also safe for daily, year round use in both rinse off and leave on formulas.
Potential Side Effects/Adverse Reactions
Reactions to topical sodium hydroxymethylglycinate differ from person to person. The points below list potential issues yet most users do not experience them when the preservative is used at the low levels allowed in cosmetics.
- Mild skin irritation
- Eye irritation if the product gets into the eyes
- Allergic contact dermatitis in individuals sensitive to formaldehyde releasers
If any irritation, burning or rash appears stop using the product and speak with a healthcare provider.
Comedogenic Rating
Rating: 0/5
Sodium hydroxymethylglycinate is fully water-soluble and used at tiny concentrations, usually below 1 percent, so it rinses away easily and does not form an oily film that could block pores. The molecule is also very small which lowers the chance of it lingering inside follicles. For these reasons it earns a solid zero on the comedogenic scale.
That makes the preservative suitable for people who are prone to acne or frequent breakouts.
Because the ingredient is present at such low levels, the overall pore-clogging risk of a finished product will depend far more on the other oils, butters or silicones in the formula than on this preservative itself.
Summary
Sodium hydroxymethylglycinate acts mainly as a broad-spectrum preservative and a mild hair conditioner. It keeps creams, lotions and cleansers free from bacteria and mold by slowly releasing trace amounts of formaldehyde that disrupt microbial growth. On the hair side it offers a slight smoothing effect that can cut down on tangles without weighing strands down.
The ingredient enjoyed a surge of popularity in the 1990s and early 2000s with brands looking for a gentler alternative to older parabens though its use has cooled in recent years because some shoppers prefer completely formaldehyde-free options.
When formulated within the legal limits it is considered safe for most skin types including sensitive, with irritation being rare and usually tied to formaldehyde allergies. As with any new skincare or haircare product it is smart to do a quick patch test before full use just to make sure your skin stays happy.