Ingredient review

Methyl Methoxycinnamate

INCI: METHYL METHYLUNDECYLIDENE-AMINOBENZOATE

A synthetic UVB filter that helps protect skin from sunburn, but its use is declining due to safety and environmental concerns.

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In plain English

This is a man-made ingredient added to sunscreens to absorb ultraviolet B (UVB) rays, which are the main cause of sunburn. It works by converting UV light into heat, which then dissipates from the skin. While effective, some studies have raised questions about its potential to mimic hormones in the body, and it has been linked to coral reef damage, leading to bans in certain regions.

Review score

Safety, usefulness, and evidence

3.5Good
3.5/ 5

Potentially useful with some tradeoffs

The evidence base is useful, but some claims depend heavily on the formula.

Risk flags are low for most users, though the finished product can still irritate.

Source
synthetic
Evidence
moderate
Irritation
low
Clogging risk
low
How reviews are scored

Quick decision guide

Useful, but context matters

Methyl Methoxycinnamate is generally a lower-concern ingredient when the full formula suits your skin.

Plain-English read

Treat this as a practical screening step before you compare products that contain this ingredient.

  1. Step 1Start with the score, then check the irritation and clogging risk before judging Methyl Methoxycinnamate.
  2. Step 2Use the "Best for" and "Use caution if" sections to match the ingredient to your skin, not just to a marketing claim.
  3. Step 3If a product stings, breaks you out, or worsens irritation, judge the finished formula and stop using it even if the ingredient scores well.

Score terms in plain English

Irritation risk

low

Less likely to sting, burn, or bother most users, though sensitive skin can still react.

Clogging risk

low

Less likely to feel heavy or contribute to clogged pores for most skin types.

Evidence level

moderate

There is useful support, but formula details and claim strength still matter.

What it is

A synthetic organic compound derived from aminobenzoic acid, designed to absorb UVB radiation (280–320 nm). It is a clear, oily liquid that blends easily into sunscreen formulations.

How it works

When applied to the skin, the ingredient absorbs UVB photons and releases the energy as heat, preventing the rays from penetrating deeper and causing DNA damage. It is often combined with other UV filters to provide broad-spectrum protection.

Pros

Effective UVB blocker

Absorbs UVB rays efficiently, reducing the risk of sunburn when used as directed.

Good formulation stability

Remains effective in products for extended periods without degrading quickly.

Cons and cautions

Environmental concerns

Has been shown to bleach coral reefs and accumulate in marine life, leading to bans in places like Hawaii and Key West.

Potential endocrine effects

Some animal studies suggest it may mimic estrogen, though human relevance is still debated and not conclusive.

Best for

  • People looking for affordable UVB protection
  • Those without sensitive skin

Use caution if

  • Pregnant or nursing individuals (due to endocrine concerns)
  • Reef-conscious consumers
  • Those with very sensitive or allergy-prone skin

Usage tips

Apply sunscreen generously 15 minutes before sun exposure.
Reapply every two hours or after swimming/sweating.
Combine with a broad-spectrum sunscreen for UVA protection.

Safety summary

Generally recognized as safe for topical use at approved concentrations, but concerns about endocrine disruption and environmental impact have led to reduced usage and regional bans.

Research notes

Animal studies indicate potential endocrine activity, but human studies are limited and inconsistent. Environmental toxicity is well-documented, particularly for coral reefs.

Common label clues

Typical concentration
Up to 10% in leave-on products
Regulatory status
Approved by the FDA in the US at concentrations up to 10% for sunscreens. Banned in some regions (e.g., Hawaii, Palau) due to environmental concerns.
Common uses
Sunscreens, SPF moisturizers, Lip balms
Environmental note
Studies show this ingredient can cause coral bleaching and harm marine ecosystems. Avoid if you swim in oceans or lakes.

Good to know

  • This ingredient is sometimes listed under the trade name 'Parsol MCX'.
  • It is not recommended for use in products marketed as 'reef-safe'.

Common questions

What is Methyl Methoxycinnamate in beauty products?

This is a man-made ingredient added to sunscreens to absorb ultraviolet B (UVB) rays, which are the main cause of sunburn. It works by converting UV light into heat, which then dissipates from the skin. While effective, some studies have raised questions about its potential to mimic hormones in the body, and it has been linked to coral reef damage, leading to bans in certain regions.

What does Methyl Methoxycinnamate do in a beauty product?

When applied to the skin, the ingredient absorbs UVB photons and releases the energy as heat, preventing the rays from penetrating deeper and causing DNA damage. It is often combined with other UV filters to provide broad-spectrum protection.

Is Methyl Methoxycinnamate safe for most people?

Generally recognized as safe for topical use at approved concentrations, but concerns about endocrine disruption and environmental impact have led to reduced usage and regional bans.

Who should be careful with Methyl Methoxycinnamate?

Pregnant or nursing individuals (due to endocrine concerns) Reef-conscious consumers Those with very sensitive or allergy-prone skin

Research sources

FDA Sunscreen MonographOpenEnvironmental Health Perspectives - Endocrine EffectsOpenNational Oceanic and Atmospheric Administration (NOAA) - Coral Reef ImpactsOpen

Ingredient reviews are educational and are not medical advice. Patch test new products and ask a licensed clinician about persistent irritation, allergies, pregnancy-specific questions, or diagnosed skin conditions.