Methionine

meh-THY-oh-neen

Protein 8/10 Safety CG ApprovedClean Semi-synthetic Vegan

What Is Methionine?

An essential sulfur-containing amino acid that the body cannot produce on its own. It is a precursor to cysteine and plays a critical role in hair growth and structural strength.

Source: Synthesized or extracted from plant/animal sources

Origin: Semi-synthetic

Also known as: L-Methionine, DL-Methionine

What Does Methionine Do to Your Hair?

Supports hair growth by providing sulfur for keratin synthesis. Acts as an antioxidant that protects hair follicles from oxidative stress. Helps maintain the structural integrity of the hair shaft through sulfur-containing protein support.

Best For

Thinning hair, slow-growing hair, damaged hair, aging hair

Not Recommended For

None known

Concentration Matters

0.1-1% in hair products

Hair Type Compatibility

1A Straight Fine
1B Straight Medium
1C Straight Coarse
2A Wavy Fine
2B Wavy Medium
2C Wavy Coarse
3A Curly Loose
3B Curly Tight
3C Curly Corkscrew
4A Coily S-Shaped
4B Coily Z-Shaped
4C Coily Tight
Heat-damaged: Beneficial

Method Compatibility

Curly Girl (CG) Method: Approved
CG Approved

Safety & Regulation

8/10
AvoidCautionSafe

Safe for topical cosmetic use. Also commonly taken as a dietary supplement for hair growth. Low toxicity and well-tolerated. Essential amino acid with important biological functions.

FDA Status: Generally Recognized As Safe

FDA considers safe for cosmetic and supplement use.

EWG Score: 1/10

HairAide Verdict

An important building block for hair growth that works best as part of a comprehensive amino acid complex. Most beneficial when hair is thin or slow-growing due to nutritional deficiency.

Products That Contain Methionine

Hair growth treatments, strengthening products, scalp serums, supplements

Alternatives to Methionine

If you want to avoid Methionine, look for products with these ingredients instead:

Cysteine, Biotin, Keratin

Frequently Asked Questions

Is Methionine safe for hair?

Yes, Methionine has a safety rating of 8/10 and is generally considered safe for use in hair products. Safe for topical cosmetic use. Also commonly taken as a dietary supplement for hair growth. Low toxicity and well-tolerated. Essential amino acid with important biological functions.

Is Methionine bad for curly hair?

Methionine is CG-method approved and is generally considered safe for curly hair.

Is Methionine CG-method approved?

Yes, Methionine is approved for the Curly Girl method.

What can I use instead of Methionine?

Some alternatives to Methionine include: Cysteine, Biotin, Keratin

Get Our Free Ingredient Decoder Cheat Sheet

Take the guesswork out of reading product labels. Our printable cheat sheet helps you decode ingredients while you shop.

Check What's In Your Products

Use our free Hair Product Label Analyzer to check any product's ingredient list instantly.

Analyze My Product →