Meradimate Safety: A Weak UVA Filter, Thinly Studied

Is Meradimate Safe? The Short Answer

No regulator has found a problem with meradimate, and none has been able to clear it either. The FDA proposed Category III for it in its 2019 review — "The public record does not contain sufficient data to support a positive GRASE determination for … meradimate … at this time" — and the 2021 proposed order that replaced that rulemaking proposes requirements "substantively the same" as the 2019 rule, with scientific discussions that "are generally the same." Neither has been finalized, which is why meradimate is still marketable.

The gap is specific. Of the ten filters with the largest data gaps, the FDA noted that only homosalate, octinoxate and octisalate "appear to have been evaluated in human absorption studies." Meradimate was not among the three, and none of the ten has been through an adequate maximal-usage trial. So the amount of meradimate that reaches the bloodstream from a normal application has never been measured.

Meradimate is, however, covered by the deferral request the FDA received for eight ingredients — unlike the truly abandoned actives, its file is still open.

For a reader choosing a sunscreen, the efficacy problem arrives first. Meradimate is marketed as a UVA filter but absorbs only at the short end of UVA and fades fast under sun, so a product leaning on it for UVA protection is not giving you much. Look for avobenzone or zinc oxide instead, and the safety question stops mattering.

Chemical Properties and UV Protection

Meradimate is an ester of anthranilic acid and menthol, approved at up to 5% concentration in the US. Despite being marketed as a UVA filter, it provides minimal protection compared to modern alternatives and is rarely used in contemporary formulations.

Inadequate UV Coverage

Meradimate's protection profile is notably poor:

• Peak absorption at 336 nm (UVA II only)
• Narrow absorption band
• No UVB protection
• Minimal protection against UVA I (340-400 nm)
• Weak extinction coefficient requiring high concentrations

Even at maximum concentration, meradimate provides insufficient UVA protection, failing to cover the critical long-wave UVA spectrum that causes photoaging and contributes to skin cancer.

Photostability Issues

Stability problems include:

• Breaks down faster than it can protect
• Forms unknown photodegradation products
• Cannot be effectively stabilized
• Requires constant reapplication

Limited Safety Data

Meradimate lacks comprehensive safety assessment:

• No absorption studies: Systemic exposure unknown
• No endocrine testing: Hormonal effects unstudied
• Minimal toxicology data: Long-term effects unknown
• No environmental assessment: Ecological impact unstudied
• Limited allergy data: Sensitization potential unclear

The absence of modern safety data is concerning, particularly given its poor performance doesn't justify the unknown risks.

Formulation Challenges

Meradimate presents multiple formulation difficulties:

• Oil soluble, limiting product types
• Strong menthol odor affects fragrance
• May crystallize in formulations
• Incompatible with some ingredients
• Difficult to achieve uniform distribution

Market Obsolescence

Meradimate has effectively vanished from the market:

• Rarely found in current US products
• Not approved in EU, Australia, or Japan
• Replaced by superior UVA filters
• May appear in very old stock

Modern UVA filters like avobenzone (despite its flaws) provide dramatically superior protection, making meradimate obsolete.

Regulatory Status

United States: Approved at up to 5% concentration. FDA has not determined GRASE status due to insufficient data.

European Union: Not approved for cosmetic use.

International status: Generally not approved globally. Where permitted, virtually unused.

Comparison to Effective UVA Filters

Historical Context

Meradimate's approval reflects outdated standards:

1. Approved when UVA protection was poorly understood
2. Grandfathered despite inadequate performance
3. Never updated to modern requirements
4. Persists in regulations through inertia

Risk-Benefit Analysis

No Meaningful Benefits

• Insufficient UVA protection
• Poor photostability
• Formulation challenges
• Unpleasant odor

Unknown but Unnecessary Risks

• No safety data
• Unknown absorption
• Unstudied health effects
• Photodegradation products

Recommendations

Given meradimate's complete inadequacy as a UVA filter:

• Never rely on meradimate for UVA protection: It simply doesn't work effectively
• Avoid any products containing it: Indicates outdated or substandard formulation
• Choose proven UVA filters: Zinc oxide, stabilized avobenzone, or bemotrizinol (GRASE since June 2026)
• Question product quality: Meradimate use suggests poor formulation choices

Meradimate exemplifies why not all approved ingredients are acceptable choices. Its weak protection, poor stability, and lack of safety data make it unsuitable for modern sun protection. Any manufacturer still using meradimate is either working from decades-old formulations or prioritizing cost over efficacy. Consumers should view meradimate as a red flag indicating a product that fails to meet current standards for UVA protection. With numerous superior alternatives available, there is no justification for meradimate's presence in contemporary sunscreens.

Recommended: ISDIN Eryfotona Actinica SPF 50 — a meradimate-free mineral alternative — zinc oxide for real UVA coverage