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# Diphtheria vaccine (diphtheria toxoid)

Inactivated diphtheria toxin that induces antitoxin antibodies. It is almost always combined with tetanus and pertussis (DTP, pentavalent, Td).

Updated 2026-11-01

- Class: [Bacterial and antimalarial vaccines](https://durgical.com/en/pharmacology/classes/bacterial-and-antimalarial-vaccines/)
- Target: Immune response against diphtheria toxin
- ATC code: J07AF01
- WHO Model List of Essential Medicines

Also called: Diphtheria toxoid, DTP / Td (combinations)

◆**Immune response against diphtheria toxin**Diphtheria vaccine (diphtheria toxoid)

ⓘ The figure shows monomeric diphtheria toxin from Corynebacterium diphtheriae; the vaccine contains this toxin in inactivated form (toxoid).

**Target in 3D:** Immune response against diphtheria toxin. PDB structure 1MDT (RCSB PDB, public domain). [View the structure at RCSB PDB](https://www.rcsb.org/structure/1MDT) · Drag to rotate · pinch to zoom

## Mechanism of action

Diphtheria is a toxin-mediated disease: only strains infected by a bacteriophage carrying the toxin gene make toxin. The toxin inhibits protein synthesis, forms the pseudomembrane and damages the heart and nerves. The toxoid induces IgG that neutralises the toxin; it protects against disease although it does not fully stop carriage.

- Diphtheria toxoid is injected, almost always in a combination vaccine
- Antitoxin antibodies and memory form
- IgG neutralises the toxin before it enters cells
- No free toxin means no pseudomembrane, myocarditis or neuritis

## Pharmacokinetics

**Onset and duration**
Protection needs the primary series and boosters to last

## Indications

- Childhood series in combination vaccines with tetanus and pertussis
- Boosters in adolescents and adults (Td) and vaccination of diphtheria survivors during recovery

## Adverse effects

### Common

- Local pain and swelling
- Low-grade fever, irritability in children

### Serious (rare, important)

- Arthus-type reaction (rare)
- Anaphylaxis (very rare)

## Contraindications

- Previous anaphylaxis to a dose or a component
- For pertussis-containing combinations: encephalopathy with no other cause within seven days of a previous dose

## Key interactions

**Diphtheria antitoxin**
Not mutually exclusive: a survivor treated with antitoxin starts or completes vaccination on recovery

## What is monitored

- Vaccination series complete for age
- Local and systemic reactions after the dose

## Administration and safety

- Intramuscular route
- Confirm the formulation (paediatric DTP or adult Td) for age, as they carry different amounts of toxoid
- Record the batch and product given

## Nursing care

- Check the vaccination card before giving
- Ask about reactions to previous doses
- Watch for fever and local reaction, and teach the family the warning signs

## Pregnancy and breastfeeding

Td can be used in pregnancy when the woman is not protected.

## Memory aid

Diphtheria = "phage + toxin": without the phage the bacterium makes no toxin, and without toxin there is no disease; the toxoid trains against that toxin.

## Test yourself

Think of the answer, then tap the question to see it.

## Why do not all Corynebacterium diphtheriae strains cause severe diphtheria?

Only strains infected by a bacteriophage carrying the toxin gene produce toxin.

## What are the most frequent complications of diphtheria?

Myocarditis and neuritis, caused by circulating toxin.

## Why should a diphtheria survivor be vaccinated?

The disease does not always leave immunity; vaccination with toxoid is completed during recovery.

[Add to my cards (3)](https://durgical.app/estudiar/?add=/en/pharmacology/diphtheria-vaccine/)

## Related drugs

- [Diphtheria antitoxin (equine)](https://durgical.com/en/pharmacology/diphtheria-antitoxin/)
- [Tetanus vaccine (tetanus toxoid)](https://durgical.com/en/pharmacology/tetanus-vaccine/)
- [Pertussis vaccine](https://durgical.com/en/pharmacology/pertussis-vaccine/)

[← Back to the class: Bacterial and antimalarial vaccines](https://durgical.com/en/pharmacology/classes/bacterial-and-antimalarial-vaccines/)

Educational content on how drugs work; not a prescribing guide and no substitute for a health professional's advice. No doses are given.

Sources: [Diphtheria](https://www.who.int/news-room/fact-sheets/detail/diphtheria) (World Health Organization, 2026); [Chapter 7: Diphtheria | Pink Book | CDC](https://www.cdc.gov/pinkbook/hcp/table-of-contents/chapter-7-diphtheria.html) (Centers for Disease Control and Prevention, 2021); [ATCDDD - ATC/DDD Index](https://atcddd.fhi.no/atc_ddd_index/?code=J07AF01) (WHO Collaborating Centre for Drug Statistics Methodology, 2026); [eEML - Electronic Essential Medicines List](https://list.essentialmeds.org/) (World Health Organization, 2025).

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Representative model, for educational purposes only.

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License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Cite as: DurgiPedia (durgical.com), https://durgical.com/en/pharmacology/diphtheria-vaccine/