Tetanus

Tetanus is a rare, entirely preventable, and non-contagious neurologic emergency caused by Clostridium tetani, an anaerobic, spore-forming, gram-positive bacillus found ubiquitously in soil, dust, and animal or human feces. Its spores are hardy, survive for years outside the body, and germinate into toxin-producing bacteria only when introduced into devitalized, oxygen-poor tissue — a puncture wound, a crush injury, a chronic ulcer, or any wound with dead tissue and poor blood supply.^[1][2]

The vegetative bacteria produce tetanospasmin, one of the most potent toxins known. Tetanospasmin binds irreversibly to peripheral motor nerve terminals and travels by retrograde axonal transport into the central nervous system, where it destroys a synaptic vesicle protein required for the release of glycine and GABA — the spinal cord and brainstem's principal inhibitory neurotransmitters.^[2] With inhibitory tone lost, motor neurons fire under unopposed excitatory drive, producing the sustained muscle rigidity and violent spasms that define the disease; in severe cases, disinhibition of autonomic neurons produces a labile, overactive sympathetic nervous system as well.^[2]

Unlike almost every other condition in this platform's infectious disease library, tetanus is never transmitted person to person — there is no human reservoir, no outbreak to trace, and herd immunity plays no role whatsoever in its prevention. Protection is entirely individual: it depends on that specific patient's own vaccination status at the moment of an injury.^[1]

Four clinical patterns

Opisthotonus in a patient with tetanus, painted by Sir Charles Bell in 1809 from his documentation of wounded soldiers after the Battle of Corunna — the same descending rigidity and spasm pattern described above, unchanged in two centuries of clinical description. (Sir Charles Bell, 1809; public domain, Wikimedia Commons)

Incubation period tracks with prognosis

Incubation is typically 3 to 21 days from inoculation to first symptom (average about 10 days), though it can range from a single day to several months depending on the distance of the wound from the central nervous system.^[1] This is a genuinely useful prognostic marker: the shorter the incubation period and the faster symptoms progress once they start, the worse the expected course — a relationship formalized in bedside prognostic scoring systems that also weigh wound type, opioid use disorder, fever, and tachycardia (see Assessment & Diagnosis).^[2]

A bedside clue worth knowing: the spatula test

Touching the posterior pharyngeal wall with a tongue depressor normally provokes a gag reflex that pushes the spatula back out. In a patient with trismus from tetanus, the same stimulus instead provokes an involuntary bite/spasm of the masseter, trapping the spatula against the teeth — a simple, specific bedside finding that helps distinguish tetanus-related trismus from other causes of a stiff jaw.^[2]

• Any wound significantly contaminated with dirt, dust, soil, animal or human feces, or saliva (including animal bites) — even one that looks small or trivial on the surface.^[1]
• Puncture wounds, avulsions, and wounds from missiles (gunshot), crush injury, burns, or frostbite.^[1]
• Any wound with devitalized (dead) tissue, or a wound/burn for which surgical care is delayed more than 6 hours.^[1]
• Chronic wounds — abscesses, cellulitis, and chronic ulcers, particularly in patients with diabetes mellitus or a history of injection drug use.^[1]
• Clinical evidence of sepsis in the wound itself.^[1]
• Occupational or recreational soil contact — farming, gardening, landscaping, and soil-testing/environmental work are all recognized exposures, and can cause tetanus from injuries that seem minor at the time (see the Saskatchewan case in Special Populations).^[4]
• Injection drug use, particularly subcutaneous/intramuscular injection ("skin-popping") — the same anaerobic-wound mechanism implicated in wound botulism.^[1]
• Older age: Canadians 75 and older have nearly four times the tetanus incidence of those under 75, driven by a combination of waning vaccine-induced immunity and infrequent adult booster uptake.^[3]
• Any gap in documented vaccination history — birth outside Canada, incomplete or lost records, no recollection of prior doses, or a caregiver who declined childhood immunization.^[1]
• Humoral immune deficiency (e.g., HIV, agammaglobulinemia, hypogammaglobulinemia) or an immunosuppressive medication, which can blunt the antibody response to tetanus-containing vaccine and change the prophylaxis decision (see Special Populations).^[1]

Tetanus is a clinical diagnosis

There is no rapid, reliable laboratory test for tetanus. Diagnosis rests entirely on the history and examination — the pattern of rigidity and spasm described in Recognize the Condition — and treatment should never be delayed while awaiting any test result.^[2][1] The Public Health Agency of Canada's national case definition confirms a case on clinical grounds alone: acute-onset hypertonia and/or painful muscular contractions (usually of the jaw and neck) plus generalized muscle spasms, without another apparent medical cause, with or without isolation of C. tetani from a wound and with or without a history of an identifiable injury — wound culture is frequently negative even in genuine disease and is not required to confirm the diagnosis.^[5]

Differential diagnosis

Consider alternative diagnoses when the picture is atypical, particularly in a fully immunized patient:

• Acute dystonic drug reaction (metoclopramide, first-generation antipsychotics, other dopamine antagonists) — usually resolves with an anticholinergic/antihistamine, and lacks tetanus's progressive rigidity and autonomic instability.
• Hypocalcemic tetany — carpopedal spasm and a positive Chvostek's/Trousseau's sign point here rather than to tetanus.
• Strychnine poisoning — can closely mimic generalized tetanus, but muscles typically fully relax between spasms, unlike the sustained background rigidity of tetanus.
• Temporomandibular joint dysfunction or a dental/peritonsillar abscess — a much more common cause of a "stiff jaw" than tetanus, but should still prompt a tetanus risk assessment of any associated wound.
• Meningitis or encephalitis — neck stiffness is shared, but fever, headache, and altered mental status point away from tetanus, which classically spares mentation throughout.^[2]

A simple bedside clue and a prognostic scoring framework

The spatula test described in Recognize the Condition is a useful, specific bedside discriminator for tetanus-related trismus. Once the diagnosis is suspected, prognosis is estimated from readily available bedside factors, with one point assigned for each of: incubation period under 7 days, time from first symptom to first spasm under 48 hours, a high-risk wound source (burns, surgical wounds, septic abortion, umbilical stump, open fracture, or intramuscular injection), opioid use disorder, generalized (rather than localized/cephalic) disease, temperature over 40°C, and heart rate over 120/min (150/min in neonates). Reported mortality rises from under 10% at a score of 0-1 to over 50% at a score of 5-6.^[2]

• Prevent tetanus before it starts — the single highest-value action, achieved through a structured, correct wound-prophylaxis decision (vaccine, TIG, both, or neither) at every tetanus-prone injury.
• In active disease: stop further toxin production at the source through prompt, thorough wound debridement.
• Neutralize any circulating, unbound toxin as early as possible with tetanus immune globulin — TIG cannot reverse toxin that has already bound to nerve terminals.
• Control muscle rigidity and spasm to prevent exhaustion, fractures, rhabdomyolysis, and respiratory compromise.
• Anticipate and manage autonomic instability proactively rather than reactively — it is a leading cause of death in severe disease.
• Protect the airway before overt respiratory failure develops, and provide meticulous ICU-level supportive and nutritional care through what can be a weeks-long recovery.
• Complete active immunization after recovery — surviving tetanus does not confer immunity against a future episode.

Step 1 — Classify the wound

Step 2 — Match wound type and vaccination history to the indicated prophylaxis

This table reflects current Canadian public health guidance, built on the National Advisory Committee on Immunization's Canadian Immunization Guide, for tetanus post-exposure prophylaxis in wound management.^[1][6]

^*Exception: a patient with humoral immune deficiency (e.g., HIV, agammaglobulinemia, hypogammaglobulinemia) or on an immunosuppressive medication may not mount an adequate response to vaccine alone. For any wound other than clean/minor, give both TIG and an age-appropriate vaccine dose regardless of how much time has passed since the last dose — consult the Medical Officer of Health as needed.^[1]

When both vaccine and TIG are indicated, give them at the same visit but at different anatomical sites with separate needles/syringes — never mix them or give both in the same limb. Do not give tetanus-containing vaccine into the gluteal region.^[1]

Which vaccine, by age

^[1]

Primary series and routine boosters — the other half of prevention

Complete protection is a primary series of at least 3 appropriately spaced doses, after which more than 99% of vaccinees develop protective antibody levels, followed by a booster every 10 years — or earlier, per the table above, if a tetanus-prone wound occurs in between.^[6][1] Every wound encounter is also an opportunity to check whether a patient is even due for their routine decennial booster, independent of the wound itself.

Tetanus immune globulin — dosing, and why prophylaxis and treatment doses differ

TIG is a human-plasma-derived product providing immediate passive protection until the patient's own vaccine-driven immunity develops.^[1] For wound prophylaxis, the standard dose is 250 units given by deep intramuscular injection in patients 7 years and older (4 units/kg in younger children).^[7] This is a much smaller dose than what is used to treat established clinical tetanus (see Special Populations and the Drug Tables), where historical regimens ranged as high as 3,000-6,000 units, though more recent evidence suggests 500 units achieves comparable effect.^[2][8] Give TIG as soon as possible after a tetanus-prone wound is identified; in a completely unimmunized patient it can still be considered up to 21 days after injury, together with vaccine.^[1]

• Clean and, where indicated, debride every wound thoroughly — this is the foundation of both prophylaxis and active-disease management, since it removes the anaerobic environment the organism needs to keep producing toxin.^[1][2]
• In active tetanus, nurse the patient in a quiet, dimly lit, low-stimulation room — spasms are triggered and worsened by light, noise, and touch, so minimizing unnecessary handling and stimulation is a genuine part of therapy, not just comfort care.^[2]
• Admit every case of active/suspected tetanus to an ICU-capable setting with continuous cardiorespiratory and autonomic monitoring, and a proactive, low threshold for securing the airway before overt respiratory failure develops.^[2]
• Prefer tracheostomy over prolonged endotracheal intubation when ventilatory support extends beyond about 10 days — an endotracheal tube itself can stimulate spasms.^[2]
• Provide high-calorie nutritional support (enteral or parenteral as needed) — the metabolic demands of sustained muscle contraction are substantial, and the illness and recovery are protracted.^[2]
• Standard precautions are sufficient throughout — tetanus is not transmitted person to person, so no isolation is required.^[1]
• Arrange physical and rehabilitation therapy proactively as spasms ease, since recovery from severe disease is measured in weeks to months.^[2]

Older adults

Canadians 75 and older have nearly quadruple (3.87 times) the tetanus incidence of those under 75, representing the age group at highest documented risk nationally — driven by waning vaccine-induced immunity decades after a childhood series, combined with low uptake of the routine 10-year adult booster.^[3] Every wound encounter, and ideally every periodic medication review, in an older adult is a genuine opportunity to check booster status rather than assuming a long-ago childhood series is still protective.

People who inject drugs

Maintain a high index of suspicion for tetanus risk in any wound related to injection drug use, particularly subcutaneous/intramuscular injection — the same anaerobic-wound mechanism responsible for wound botulism in this population.^[1] These patients are also disproportionately likely to have an incomplete or unknown vaccination history, and this encounter is a genuine opportunity for harm-reduction engagement alongside the tetanus assessment itself.

Occupational and recreational soil exposure

A 2023 Canadian case report illustrates how easily this risk is missed: a 33-year-old Saskatchewan soil-testing technologist with occupational dirt exposure across three prairie provinces developed generalized tetanus 10 days after small, self-treated hand abrasions from a physical altercation — abrasions minor enough that he never sought medical attention for them at the time. His vaccination history included at least 5 childhood doses but none in adulthood, with his last dose roughly 20 years earlier. He required 17 days of hospitalization, including ICU admission and intubation for hypercapnic respiratory failure, and was left with post-discharge muscle spasticity and a herniated disc requiring surgery, though he ultimately returned to work with minimal motor sequelae two years later.^[4] The case is a genuinely useful teaching example on two fronts: a small, "not worth a doctor's visit" wound can still be tetanus-prone when soil-contaminated, and a full childhood series does not remain protective indefinitely without adult boosters.

Pregnancy

Pregnancy is not a contraindication to either tetanus-containing vaccine or TIG — do not withhold indicated wound prophylaxis because a patient is pregnant. (Routine antenatal Tdap dosing for pertussis protection of the newborn is a separate, scheduled recommendation outside the scope of this wound-management chapter.)

Neonates, and Canada's maternal/neonatal tetanus elimination

Canada has formally validated the elimination of both maternal and neonatal tetanus, with zero confirmed cases identified across a national epidemiologic review spanning 1995-2019.^[3] This form of tetanus should not be encountered in Canadian pharmacy practice, but it remains a significant cause of vaccine-preventable neonatal death in regions with incomplete maternal immunization coverage, and is a useful global-health context point.

Humoral immune deficiency and immunosuppression

Patients with a humoral immune deficiency (HIV, agammaglobulinemia, hypogammaglobulinemia) or on an immunosuppressive medication may not respond adequately to tetanus-containing vaccine alone. For any wound other than clean/minor, give both TIG and an age-appropriate vaccine dose in these patients, regardless of how much time has passed since their last documented dose — consult the Medical Officer of Health if there is any uncertainty.^[1]

Diabetic foot ulcers and other chronic wounds

Chronic wounds — diabetic foot ulcers, venous or pressure ulcers, and chronic cellulitis — are classified as tetanus-prone in the wound-prophylaxis table above, precisely because they don't look like a fresh traumatic injury and are easy to overlook as a tetanus risk during routine chronic-wound care.^[1] Build a tetanus-status check into any structured wound-care follow-up for these patients.

Renal and hepatic impairment

No dose adjustment is required for tetanus-containing vaccine or TIG in renal or hepatic impairment. Among the active-treatment drugs, adjust benzodiazepine dosing/monitoring for hepatic impairment (diazepam has active metabolites that can accumulate), and reduce the magnesium sulfate infusion rate and increase monitoring frequency in renal impairment, since reduced clearance raises the risk of magnesium toxicity — watch the patellar reflex especially closely in this group.

• After giving wound prophylaxis, document exactly what was given (vaccine, TIG, or both), the anatomical site of each, and the lot number, and update the patient's own immunization record — this documentation is what allows the next tetanus-prone wound to be assessed accurately instead of defaulting to "unknown history."^[1]
• Refer any patient who received prophylaxis because of an unknown or incomplete history to Public Health to complete the full primary series — a single wound-triggered dose is not a substitute for a proper 3-dose series.^[1]
• For active/suspected tetanus, once stabilized and escalated to emergency/ICU care, monitor respiratory status, spasm frequency/severity, and autonomic parameters (heart rate, blood pressure) continuously — recovery is protracted, typically weeks, and can take months for full resolution.^[2]
• Complete a full primary tetanus vaccination series at recovery from clinical tetanus, regardless of how many doses the patient had before the illness. Surviving a natural tetanus infection does not confer future immunity — unlike most infections in this platform's library, the tiny amount of toxin involved in even a severe clinical case is far too small to trigger a durable protective antibody response. This is a genuinely high-yield, easy-to-miss point: a patient who has already "had tetanus" still needs the same full series as someone who has never had a dose.^[2][8]
• Tetanus is a nationally notifiable disease in Canada — confirm that public health reporting has occurred for any confirmed case, typically coordinated by the treating hospital.^[5]

1. Spasms continuing or worsening despite adequate benzodiazepine titration: escalate the ICU care plan — add or increase magnesium sulfate infusion, and involve critical care for propofol or neuromuscular blockade with mechanical ventilation if rigidity is truly refractory.^[2]
2. Autonomic instability (labile blood pressure/heart rate) refractory to magnesium and sedation: involve critical care/cardiology for further management; avoid non-selective beta-blockers, which have been associated with sudden cardiac death in this setting, and use a short-acting agent like esmolol only with strict titration and monitoring if a beta-blocker is felt necessary.^[2]
3. Ongoing or recurrent toxemia despite TIG and antibiotics: reassess the wound for incompletely debrided or undrained tissue and consider repeat surgical exploration — the wound remains the toxin source until it is truly controlled.^[1][2]
4. Uncertainty persists about a patient's vaccination history after reasonable effort to obtain records: treat as unimmunized/inadequately immunized per the decision table, and refer to Public Health both to pursue the records and to complete the primary series going forward — do not leave the prophylaxis decision unresolved while records are pending.^[1]
5. TIG is not immediately available at the point of care: do not delay wound care or the vaccine dose while arranging TIG access — follow local/zone processes to obtain it as soon as possible, and give it as soon as it arrives (it retains meaningful benefit for up to about 21 days post-injury in a completely unimmunized patient).^[1]

• Treating a small, "not worth a doctor's visit" wound as automatically low-risk — a soil-contaminated abrasion can cause tetanus exactly as the Saskatchewan case in Special Populations illustrates.^[4]
• Assuming a completed childhood vaccination series remains protective indefinitely — protection wanes, and the decennial booster genuinely matters, especially in older adults.^[3]
• Giving TIG and the vaccine dose in the same syringe or at the same injection site — always use separate syringes and different anatomical sites.^[1]
• Withholding indicated vaccine or TIG because a patient is pregnant — pregnancy is not a contraindication to either.
• Reaching for penicillin as the antibiotic of choice for active tetanus out of habit — its GABA-antagonist activity can worsen the disease's own core mechanism; use metronidazole instead.^[2]
• Assuming that surviving a tetanus infection confers future immunity — it does not, and the full primary series must still be completed at recovery.^[2][8]
• Delaying prophylaxis while waiting for immunization records to arrive from another province, territory, or country — make the best assessment available at the visit instead.^[1]
• Overlooking tetanus risk in chronic wounds (diabetic foot ulcers, chronic ulcers) because they don't present as a fresh traumatic injury.^[1]
• Missing tetanus in the differential for new trismus/jaw stiffness because it "looks dental" — a genuine wound history should always be asked about.
• Assuming a tick or insect bite always needs TIG regardless of vaccination history — it is treated as a clean, minor wound unless unusually deep or visibly soil-contaminated.^[1]

How to use this table: vaccine and TIG doses reflect the wound-prophylaxis decision table in Choose Initial Treatment; ICU drug doses require patient-specific confirmation (renal/hepatic function, weight, concurrent sedation) and are shown for context, not community initiation. Select any drug name to open its complete Pharmasist Drug Database page.

Tetanus Toxoid-Containing Vaccines — Active Immunization

See Choose Initial Treatment for the full wound-prophylaxis decision table and age-appropriate vaccine selection.

Tetanus Immunoglobulin (TIG) — Passive Immunization

Prophylaxis and treatment doses differ substantially — see the dose column. Always give at a different anatomical site than the vaccine dose, using a separate syringe.

Antimicrobial Therapy for Active Tetanus

Antibiotics treat the local wound infection/organism burden — they do not neutralize circulating toxin, which is TIG's role.

Spasm and Autonomic Control (ICU Setting)

Meticulous, individualized titration in an ICU setting is standard — these are not community-pharmacy-initiated therapies, but pharmacists should understand the regimen a hospitalized patient is on.