Codification of GHS H-Codes & P-Codes: Complete Guide 2026

Hazard statement codes (H-Codes) 

Hazard statement codes are grouped by the first digit into three broad categories: 

Examples:

This numbering system exists because it supports consistent classification across languages and jurisdictions. A safety professional reviewing an SDS from a supplier in Germany, Japan, or Brazil can immediately recognize that an “H3xx” code relates to a health hazard, even without reading the full translated text. This consistency is a major part of why GHS adoption has improved cross-border chemical safety communication.

Precautionary statement codes (P-Codes) 

Precautionary statement codes follow a similar logic, grouped into five functional categories: 

Examples: 

Employees must keep in mind that some precautionary statements, such as P305+P351+P338 above, combine many codes into a single instruction. It's intentional. Many response activities tend to naturally occur together as a sequence; hence, combined P-codes are used to eliminate repetition and label clutter. It consolidates the three overlapping instructions into a single, unambiguous, actionable statement. The merged code makes labels easier to read without losing vital safety information. 

How are hazard statements assigned? 

Hazard statements are not selected by the manufacturer or the writer of the label but are the product of a systematic hazard classification process. This method often includes:  

• Hazard classification–Assessment of the chemical (or mixture) against the prescribed GHS criteria to classify the relevant hazard classes. 

• Hazard categories – Chemicals are further categorized into categories within each hazard class that indicate severity (for example, Category 1 is generally the most severe hazard within a class). 

• Physical hazards – Assessed by standardized test procedures (e.g., flammability, explosivity, oxidizing potential). 

• Health hazards – Determined based on toxicological data, existing research, or read-across from structurally comparable chemicals. 

• Environmental hazards – Based on aquatic toxicity and environmental persistence/bioaccumulation data. 

• Testing – The data for classification is generated by physical and toxicological testing (or verified alternative methods). 

• Supplier responsibility—The chemical maker or importer is responsible for the right classification of the hazard in compliance with the applicable regulatory procedures. 

In other words, danger statements are not randomly assigned but are based on the chemical's GHS categorization. Once a danger class and category are determined, the H-code and the exact phrasing of the statement are required and there is no choice as to how to word the statement. 

How are precautionary statements selected? 

Unlike hazard statements, which are a direct one-to-one output of classification, precautionary statement selection involves a bit more judgment. GHS guidance allows label authors some flexibility in choosing which precautionary statements are most relevant, based on factors such as the following: 

• Hazard category—The severity and type of hazard influence which precautionary measures are appropriate. 

• Exposure routes – Whether the primary risk is through inhalation, skin contact, ingestion, or eye contact. 

• Storage – Specific conditions needed to prevent degradation, reaction, or accidental release. 

• Disposal – Requirements based on the chemical's classification and local waste regulations. 

• Emergency response – What actions are most critical if exposure or an incident occurs. 

Relationship between H-Codes and P-Codes 

Because hazard statements describe what’s wrong, and precautionary statements describe what to do about it, the two are deeply interconnected. Each hazard classification typically has a recommended set of associated precautionary statements, though, as noted above, not all of them need to appear on a given label. 

This mapping is one of the most useful things to understand about the codification system, because it shows the logical chain from hazard to protective action: classification determines the hazard statement, and the hazard statement, in turn, points toward a defined set of appropriate precautionary responses. Once this relationship clicks, reading an unfamiliar SDS or label becomes far less intimidating — even a long list of codes starts to read as a coherent risk-and-response story rather than a wall of jargon. 

Where do H-codes and P-codes appear? 

Hazard and precautionary statements aren't confined to just one document — they appear in two primary places: the product label and the Safety Data Sheet. 

On GHS labels 

A compliant GHS label includes several standardized elements working together, including: 

• Product identifier 

• Signal word 

• Pictograms 

• Hazard statements 

• Precautionary statements 

• Supplier information 

Here, the hazard and precautionary statements are displayed as full text (not just the code), giving workers immediate, readable information without needing to reference a separate document. 

On safety data sheets 

Within the 16-section SDS format, hazard and precautionary statements appear primarily in Section 2: Hazard Identification, which lists the chemical GHS classification, applicable hazard statements, precautionary statements, and signal word. However, elements of this information may also be referenced or expanded upon in other sections — such as Section 4 (First-Aid Measures), Section 7 (Handling and Storage), and Section 13 (Disposal Considerations) — since these sections elaborate on the practical application of the precautionary statements introduced in Section 2. 

Hazard statements vs. precautionary statements 

Because these two code types are so closely linked, it helps to see them side by side:

Understanding this distinction is fundamental — not just for compliance, but for effective worker training. Employees don't need to memorize every code, but they should understand that an "H" code tells them about danger, while a "P" code tells them what action to take. 

Common examples by hazard type 

To see the codification system in action, it helps to look at how H-codes and P-codes work together for specific categories of chemicals. 

Flammable chemicals 

Flammable chemicals are typically classified under the H2xx series. A common example is a highly flammable solvent classified with H225 (highly flammable liquid and vapor), which is commonly paired with precautionary statements like P210 (Keep away from heat/sparks/open flames) and P233 (keep container tightly closed). Many flammable liquid SDS documents will list these codes together in Section 2, giving a clear, at-a-glance picture of both the fire risk and the handling precautions required. 

Corrosive chemicals 

Corrosive compounds are often classed with H314 (it causes serious skin burns and eye damage). This danger is generally associated with cautious statements such as P280 (Wear protective gloves/eye protection/face protection) and the combined response statement P305+P351+P338 (IF IN EYES: Rinse off well with water…). These codes together signal both the seriousness of a chemical burn hazard and the first-aid response necessary immediately. 

Toxic chemicals 

Many toxic substances will have numerous danger statements. A toxic chemical, for example, would be H300 (Fatal if eaten) and H331 (Toxic if inhaled). They are often used in conjunction with cautious statements aimed at prevention, such as P260 (Do not breathe dust/fume/gas/mist/vapor/spray) and P264 (Wash … hands completely after handling), based on the need to prevent exposure through numerous channels. 

Oxidizers 

Oxidizing chemicals are often classified with H271 (May cause fire or explosion; strong oxidizer). Associated precautionary statements typically include P220 (Keep/store away from clothing/combustible materials) and the response statement P370+P378 (In case of fire: use appropriate extinguishing media)—reflecting both the storage precautions and emergency response needed for this hazard class.

Common mistakes in chemical labeling 

Even with a standardized system in place, labeling errors remain common — and they're often the root cause of compliance citations or workplace incidents. The most frequent mistakes include: 

• Missing H statements 

Omitting a hazard statement that applies based on the chemical's actual classification. 

• Incorrect P statements 

Including precautionary statements that don't match the listed hazards or omitting critical ones. 

• Wrong signal word 

Using "Warning" when "Danger" is required, or vice versa, based on the hazard severity. 

• Wrong pictograms  

Displaying pictograms that don't correspond to the chemical's actual hazard classification. 

• Outdated classifications 

Continuing to use hazard information based on an old SDS version after a reclassification has occurred. 

• Copying labels without verification 

It means reusing a label or SDS template from a similar product without confirming that the classification still applies. 

• Translation errors  

Introducing inconsistencies or inaccuracies when the hazard and precautionary statement text is translated for international markets. 

Because H-codes and P-codes are meant to be exact and standardized, even small deviations—like a slightly reworded hazard statement—can create compliance gaps and confuse workers who rely on consistent language safety decisions. 

Regulatory requirements 

The codification of hazard and precautionary statements underpins several major regulatory frameworks around the world: 

OSHA Hazard Communication Standard (HazCom) 

Adopts the GHS classification and labeling criteria in the United States, requiring employers and chemical manufacturers to use standardized hazard statements, precautionary statements, pictograms, and SDS formatting. 

UN GHS 

The foundational international framework from which most national regulations, including OSHA’s HazCom standard, derive their hazard statement and precautionary statement systems. 

CLP Regulation (EU)  

The European Union’s Classification, Labelling and Packaging regulation, which implements GHS principles with some region-specific additions. 

WHMIS (Canada)  

Canada’s Workplace Hazardous Materials Information System, aligned with GHS to ensure consistency with U.S. and international labeling practices. 

How does SDS management software help? 

Given the complexity of correctly classifying chemicals and assigning the right combination of H-codes and P-codes, many organizations turn to dedicated SDS management platforms like CloudSDS to reduce manual error and streamline compliance. These platforms typically support: 

• Automated classification support – Helping cross-reference chemical data with GHS classification criteria to reduce manual guesswork. 

• Centralized SDS library—Storing all Safety Data Sheets in one accessible, searchable system rather than scattered across departments or binders. 

• Label consistency – Ensuring that hazard and precautionary statements on generated labels match the underlying SDS classification exactly. 

• Version control – Tracking SDS updates and reclassifications, so outdated hazard information isn’t accidentally left in circulation. 

• Regulatory updates – Keeping classification criteria current as GHS revisions or regional regulations change. 

• Multi-language SDS access – Supporting accurate, consistent hazard communication for multinational or multilingual workforces. 

• Audit readiness – Making it easier to demonstrate compliance during OSHA inspections or internal safety audits by keeping documentation organized and traceable. 

For organizations managing hundreds or thousands of chemical products, software-driven consistency is often the difference between a label that’s technically compliant and one that’s actually accurate.

Frequently asked questions 

What are H-codes?  

Hazard statement codes, or H-codes, are the standardized alphanumeric codes (starting with "H") that characterize the nature and severity of a chemical hazard under the GHS. 

What are P-codes?  

P-codes, or precautionary statement codes, are standardized alphanumeric identifiers (starting with "P") that identify recommended procedures to prevent or reduce harm from a hazardous substance. 

Are H-codes mandatory?  

Yes. Under OSHA's Danger Communication Standard and other GHS-aligned standards, danger statements are required on both labels and Safety Data Sheets. 

Do P-codes appear on every label? 

Not always. Hazard statements are normally necessary in their entirety. However, in order to maintain readability of the label, label authors may select the most relevant precautionary statements instead of providing all linked P-codes. 

Can one chemical have multiple H-statements? 

Yes. A chemical can belong to more than one hazard class; for instance, a compound might be both flammable and poisonous, necessitating more than one hazard statement on its label and SDS. 

Why are some P-statements combined?  

Combined P-codes (e.g., P305+P351+P338) combine related response actions in a single instruction to avoid redundancy and improve the readability of the label.