A weak inorganic acid of boron, linked in EU data to an Annex II entry.
What it is
Boric acid is a weak inorganic acid of boron that forms colourless crystals or a white powder. CosIng lists it as an antimicrobial, buffering and denaturant ingredient. The EU data link this ingredient to an entry in Annex II (prohibited substances).
Where it is used
Found in a small number of products.
Limits of interpretation
The INCI list shows which ingredients are present, not how much of each. Above 1%, ingredients are listed in descending order of weight; below 1% the order is free.
See the EU regulation section for what the Annex II entry covers and how it applies.
Functions
- Antimicrobial
- Preventing and/or slowing down microbial growth.
- Buffering
- Stabilising the pH of an aqueous medium in a narrow range even if an acid or base is added. Altering and/or maintaining a cosmetic product's pH at the desired level.
- Denaturant
- Rendering cosmetics unpalatable. Mostly added to cosmetics containing ethyl alcohol to make it unsuitable for ingestion.
EU regulation
EU · Annex II, entry 1395Boric acid [1];
Boric acid [2]
- As of
- 3 November 2026 · (EU) 2019/831
Safety Gate alerts (EU)
2 alerts about dangerous cosmetics in the EU mention this substance. An alert concerns a specific product, usually one that breaks EU rules.
- Evterpa – Lotion with tea tree oil for fungal skin and nails (2020-03-17)
- Evterpа – Anti-fungal lotion on the skin (2019-10-02)