MDR Annex I Chapter III Section 23.1(h) allows information on a medical device label to be given by symbols only when those symbols come from a recognised harmonised standard. In practice that standard is EN ISO 15223-1:2021, "Medical devices — Symbols to be used with medical device labels, labelling, and information to be supplied — Part 1: General requirements." Symbols for manufacturer, manufacture date, expiry, lot, serial, single use, sterile state, "consult instructions for use," caution, and the MD symbol that satisfies the "medical device" indication in Section 23.2 all come from EN ISO 15223-1:2021. Any symbol not from a recognised standard must be described in writing in the IFU. The UDI carrier under Article 27 is not a 15223-1 symbol.

By Tibor Zechmeister and Felix Lenhard. Last updated 10 April 2026.

TL;DR

  • MDR Annex I Chapter III Section 23.1(h) of Regulation (EU) 2017/745 is the legal basis for using symbols on medical device labels. Symbols may replace text only when they come from a recognised harmonised standard or common specification.
  • The recognised standard in practice is EN ISO 15223-1:2021, "Medical devices — Symbols to be used with medical device labels, labelling, and information to be supplied — Part 1: General requirements."
  • Symbols from EN ISO 15223-1:2021 satisfy specific Section 23.2 subparagraphs: manufacturer, use-by (hourglass), LOT, and the MD symbol for the "indication that the product is a medical device" requirement.
  • Any symbol not from a recognised standard must be described in writing in the IFU. Invented symbols without explanation are a Section 23.1(h) finding.
  • Single-use, sterile, and sterilisation-method symbols compress text on small labels but do not reduce obligations — the underlying Section 23.2 requirement still applies.
  • The UDI carrier under MDR Article 27 is not part of EN ISO 15223-1:2021. It is a separate machine-readable and human-readable identifier governed by Article 27 and Annex VI Part C.

Why symbols matter more the smaller your label gets

The smaller the device, the more weight each symbol carries. A single-use implant with a primary label the size of a postage stamp cannot fit "Manufactured by," a full address, "Use by," "Do not reuse," "Sterilised by irradiation," and "Consult instructions for use" in words. It can fit the eight or nine symbols that say the same thing. This is the only way Annex I Chapter III Section 23.2 is physically achievable on a small label at all.

Where founders go wrong is treating the symbol library as decoration. The graphic designer copies icons from a competitor label, adjusts them for brand fit, and ships. A notified body auditor catches this in the first five minutes: the symbol geometry is wrong, the symbol is from an old edition of the standard, or the symbol is not in any standard at all and is unexplained in the IFU. Each of those is a finding against Annex I Section 23.1(h).

When symbols may replace text under Section 23.1(h)

Section 23.1 of Annex I sets the general principles for information supplied with the device. Paragraph (h) allows the information to be given in the form of internationally recognised symbols and requires that any symbol or identification colour used conforms to harmonised standards or common specifications. Where no harmonised standard or common specification exists, the symbols and colours must be described in the documentation supplied with the device. (Regulation (EU) 2017/745, Annex I, Chapter III, Section 23.1.)

Three rules follow. First, a symbol from a recognised standard can replace the corresponding text on the label without further explanation in the IFU — the standard carries the meaning. Second, a symbol that is not from a recognised standard must be explained in writing in the documentation supplied with the device, typically the IFU. An invented symbol without explanation is a nonconformity, even if its meaning is "obvious" to the designer. Third, the standard is not optional. Using a symbol from a recognised standard is the legal path; anything else requires the written IFU explanation.

The MDR text does not name EN ISO 15223-1 directly. It points to whatever harmonised standard covers the symbol. For medical device labels, EN ISO 15223-1:2021 is the standard that industry and notified bodies treat as the reference.

The role of EN ISO 15223-1:2021

EN ISO 15223-1:2021, "Medical devices — Symbols to be used with medical device labels, labelling and information to be supplied — Part 1: General requirements," catalogues the symbols used on medical device labels, defines their meaning, specifies their geometry, and states which symbol satisfies which type of labelling information. It is the reference library for every manufacturer using symbols instead of words to comply with Section 23.2.

Use the current edition. Earlier editions used different geometry for some symbols and lacked entries that the 2021 edition added — most notably the MD symbol that satisfies the Section 23.2 "indication that the product is a medical device" requirement. Work from the current published edition, not from clip art, competitor packaging, or an old PDF.

Which symbols a startup actually needs

A typical MDR Class I, IIa, or IIb device with an expiry, a lot code, and a sterile or single-use indication uses the same small set of EN ISO 15223-1:2021 symbols. Each maps to a subparagraph of Annex I Chapter III Section 23.2.

  • Manufacturer symbol — satisfies the manufacturer name and registered place of business requirement. Used with the manufacturer name and address printed next to the symbol.
  • Authorised representative symbol — identifies an EU authorised representative for manufacturers established outside the Union.
  • Date of manufacture symbol — satisfies the date of manufacture requirement where no expiry is given.
  • Use-by date symbol (hourglass) — satisfies the expiry requirement (at least year and month).
  • LOT symbol — satisfies the lot or batch code requirement. Replaces the printed word "LOT."
  • Serial number symbol — satisfies the serial number requirement where serial is used instead of lot.
  • Sterile symbols with sterilisation method — satisfies the sterile state and method indication.
  • Do-not-reuse (single-use) symbol — satisfies the single-use indication requirement.
  • Consult instructions for use symbol — directs the user to the IFU for detailed warnings.
  • Caution symbol — draws attention to warnings and precautions Section 23.2 requires at point of use.
  • MD symbol ("medical device") — satisfies the "indication that the product is a medical device" requirement. The newest entry in the startup toolkit and the one most pre-MDR labels were missing.

A device that fits these eleven categories can hit most of Section 23.2 with glyphs, leaving printed text for device name, manufacturer name and address, and device-specific warnings.

What EN ISO 15223-1:2021 does not cover

Two common label elements sit outside EN ISO 15223-1:2021 and are governed by their own regimes:

  • The CE marking is not a 15223-1 symbol. It is governed by MDR Article 20, with glyph geometry set in Annex II of Regulation (EC) No 765/2008. It cannot be used as a proxy for the MD symbol; for most devices, both must appear on the same label.
  • The UDI carrier under MDR Article 27 is not a 15223-1 symbol. It is a machine-readable data carrier (linear barcode, 2D matrix, or RFID tag) encoding the UDI-DI and UDI-PI, alongside a human-readable interpretation. The carrier format is set by a Commission-designated issuing entity. (Regulation (EU) 2017/745, Article 27.)

A label that treats the CE mark and the UDI carrier as "just more symbols from the library" is mixing three distinct regulatory regimes and usually gets at least one of them wrong.

Audit examples — what goes wrong in the first five minutes

Three recurring failure modes across notified body audits:

  • Invented symbols with no legend. A startup adds a "keep dry" icon copied from a cosmetics product. There is a harmonised 15223-1 symbol for "keep dry" — but the version on the label is not it. Section 23.1(h) requires an invented symbol to be described in writing in the documentation supplied with the device. No IFU explanation, no defence at audit.
  • Outdated symbol geometry. A legacy label still uses pre-2021 manufacturer and expiry symbols because the print file has not been updated. Meaning is the same; geometry is not from the current edition. Raised as a Section 23.1(h) observation, corrected at the next revision cycle.
  • Missing MD symbol. A Directive-era label never carried an "indication that the product is a medical device" because the Directives did not require it explicitly. Under Section 23.2 it is mandatory. A pre-MDR label reused after 26 May 2021 without the MD symbol is a Section 23.2 finding.

All three are preventable with a symbol legend table, a single source print file under EN ISO 13485:2016+A11:2021 document control, and a label review step that cross-checks every symbol against the current edition before the print run.

Ship — the label symbol playbook

A resource-constrained startup ships a compliant label with symbols using the same short playbook every time:

  1. Build a symbol legend table listing every symbol on the label, its EN ISO 15223-1:2021 reference, its meaning, and the Section 23.2 subparagraph it satisfies. Reproduce the legend in the IFU.
  2. Freeze the glyphs to the current edition. Source vector files from the published standard and keep them under QMS document control so they cannot drift.
  3. Cross-check every symbol against Section 23.2. If a symbol does not map to a subparagraph and is not required by another source (Article 20, Article 27, Regulation (EC) No 765/2008), it does not belong on the label.
  4. Write up non-standard symbols in the IFU. Any symbol not in EN ISO 15223-1:2021 is explained in the IFU legend. No exceptions.
  5. Add the MD symbol if the device is placed on the market under the MDR and does not already carry the text "medical device." Most common missing element on labels migrated from Directive-era certification.
  6. Separate the CE mark and the UDI carrier from the 15223-1 symbols in the artwork layout. Different regimes, not interchangeable glyphs.

Reality Check — Where do you stand?

  1. Do you have a symbol legend table mapping every symbol on your label to an EN ISO 15223-1:2021 reference and a Section 23.2 subparagraph?
  2. Are all symbols sourced from the current edition of EN ISO 15223-1:2021, with vector files under EN ISO 13485:2016+A11:2021 document control?
  3. Does your label carry the MD symbol (or the words "medical device") to satisfy the Section 23.2 "medical device" indication?
  4. Are any non-standard symbols described in writing in the IFU legend, as Section 23.1(h) requires?
  5. Is the CE mark treated separately from the 15223-1 symbols, with geometry per Annex II of Regulation (EC) No 765/2008 and the notified body four-digit number where applicable?
  6. Is the UDI carrier treated separately, with both UDI-DI and UDI-PI in machine-readable and human-readable form?
  7. For each target Member State under Article 10(11), do the symbols reduce translated text enough that every required element still fits?

Frequently Asked Questions

Which standard does MDR recognise for symbols on medical device labels? Annex I Chapter III Section 23.1(h) of Regulation (EU) 2017/745 requires symbols to come from a harmonised standard or common specification. In practice the recognised standard is EN ISO 15223-1:2021, "Medical devices — Symbols to be used with medical device labels, labelling and information to be supplied — Part 1: General requirements."

Can I invent my own symbol if there is no match in EN ISO 15223-1:2021? Only if described in writing in the documentation supplied with the device. Section 23.1(h) allows this where no harmonised standard or common specification exists. The written explanation goes in the IFU legend. An invented symbol without explanation is a Section 23.1(h) nonconformity.

Does the MD symbol satisfy the "indication that the product is a medical device" requirement? Yes. The MD symbol from EN ISO 15223-1:2021 satisfies the Section 23.2 requirement without needing the words "medical device" in text on the label. Most Directive-era labels did not carry this indication and have to be updated at the first revision after 26 May 2021.

Is the UDI carrier part of EN ISO 15223-1:2021? No. The UDI carrier is governed by MDR Article 27. It is a separate machine-readable and human-readable data carrier, not a 15223-1 symbol. The carrier format is set by a Commission-designated issuing entity and must appear on the label in addition to any 15223-1 symbols.

Can I use symbols from an earlier edition of EN ISO 15223-1? Use the current edition. The 2021 edition changed some symbol geometries and added entries (including the MD symbol) that earlier editions did not contain. Outdated geometry is an observation at audit and must be corrected at the next label revision.

Do I still need the IFU if every Section 23.2 element is covered by symbols on the label? Yes. Section 23.4 of Annex I requires the IFU in addition to the label, and Article 10(11) sets language requirements for the information supplied with the device. Symbols compress Section 23.2 text but do not replace the IFU.

Sources

  1. Regulation (EU) 2017/745 of the European Parliament and of the Council of 5 April 2017 on medical devices, Annex I Chapter III Section 23.1 (general principles for information supplied with the device, including paragraph (h) on symbols), Annex I Chapter III Section 23.2 (information on the label), Article 10(11) (language of information supplied with the device), Article 20 (CE marking of conformity), Article 27 (Unique Device Identification). Official Journal L 117, 5.5.2017.
  2. EN ISO 15223-1:2021, "Medical devices — Symbols to be used with medical device labels, labelling and information to be supplied — Part 1: General requirements".
  3. EN ISO 13485:2016 + A11:2021, "Medical devices — Quality management systems — Requirements for regulatory purposes" — document control of label artwork and symbol vector files.
  4. Regulation (EC) No 765/2008 of the European Parliament and of the Council setting out the requirements for accreditation and market surveillance relating to the marketing of products, Annex II (CE marking geometry). Official Journal L 218, 13.8.2008.

This post is part of the Technical Documentation & Labeling cluster in the Subtract to Ship: MDR blog. Authored by Felix Lenhard and Tibor Zechmeister. The symbols on a compliant label are compressed regulation, not graphic design.