Behentrimonium Methosulfate

Commonly found in:

  • Hair care
  • Skin care
  • Facial cleanser
  • Moisturizers
  • Hair relaxers
  • Hair color


Shop Now>>

Simplifica products with this ingredient:

EWG's Skin Deep Cosmetic Safety Database:

  • Safety Rating - 0
  • Data - Limited

Also identified as:

  • BTMS
  • Behenyl Trimethyl Ammonium Methosulfate
  • Docosyltrimethylammonium Methyl Sulphate

Hydrating Shampoo & Conditioner
Sleek & Shiny Shampoo & Conditioner
Curl Defining Shampoo & Conditioner
Volumizing Shampoo & Conditioner
Curl Defining Cream
Protein Hair Mask
Rooibos Tea Hand & Body Lotion
Simplicity Baby Detangler


The blend consisting of Behentrimonium methosulfate (&) Cetearyl alcohol (or BTMS) is considered the mildest conditioning hair-detangling ingredient available today. This sophisticated ingredient is a hair thickener that unlike most, does not cause build-up on the hair. This is in part due to the fact that it does not coat, but actually penetrates the hair shaft. Because it is so extremely gentle, it is recommended for use in leave-on baby products. This ingredient is not the same as behentrimonium chloride, which is not nearly as mild or gentle.

Update: This ingredient is classified as a quaternary ammonium compound. In 2009, a report was published summarizing a study of the risks associated with industrial cleaners in hospitals. It was not a study on this specific class of compounds. It actually wasn't a study on chemical compounds at all but rather more of a work flow study to determine through which activities and to what degree the cleaning staff was at risk (skin & lungs specifically) based on job requirements. The report mentions this classification of chemicals in a few places in the report. First it mentions it as an "ingredient of concern" - primarily because it was so widely used in the products they were studying. Several paragraphs later, it notes that quats have been identified as an "indoor agent that may promote development of airway allergy." However, it also indicates that this would occur through either inhaling particles delivered through an aerosol application of some type or by inhaling dust particles from the air that have somehow absorbed quats. Further comfort is found in the fact that because quats are not VOC's, their potential for inhalation is extremely low. The study also mentions some evidence from both animal and human studies that indicate quats have allergy promoting effects - but again the context suggests these are risks associated with inhalation caused by aerosol distribution. We realize there is only the weakest of links between this study and the use of behentrimonium methosulfate in cosmetics - but we did want to provide it for your consideration. We will continue looking for the studies mentioned in the report and update with any information we locate.

Although also fairly irrelevant to cosmetic use of BTMS, you may find it interesting that quaternary ammonium compounds, are also used in anesthesia as a muscle relaxant or neuromuscular-blocking drug. They help prevent spontaneous movement of muscle during surgeries by inhibiting neuron transmissions. As with virtually every other substance in existance, some people have shown hypersensitivity to the use of quaternary ammonium compounds in this application and have suffered anaphylactic reactions. In fact, studies indicate that quats are the component in anesthesia that is responsible for roughly 65% of anaphylactic reactions during surgery. Other common causes of anaphylaxis during anesthesia include opiods, penicillin, gelofusine, latex, hypnotics, antibiotics, and plasma substitutes. Skin tests can be done prior to surgery that, along with a complete medical history, can assist in identifying patients who may be vulnerable to this type of anesthesia reaction.


Please contact us if you would like additional information about this ingredient.