Phenytoin Toxicity Clinical Presentation
- Author: Charlene Miller, MD; Chief Editor: Asim Tarabar, MD more...
Establish if the toxicity is acute or chronic.
Important historical elements in acute toxicity are as follows:
- Time of ingestion
- Motivation for ingestion (intentional versus accidental)
- Medications available in the household
- Paramedics or family members may be able to provide additional information (eg, medications, past medical history)
In chronic toxicity, important historical elements are as follows:
- Duration of phenytoin use
- Compliance (last dose and missed dose)
- Recent changes in pharmacotherapy
Important elements for patient query are as follows:
- When symptoms began
- Severity of symptoms
- Exacerbating factors
- Associated problems
- Relieving factors
See the list below:
- Phenytoin may cause a febrile reaction, hypotension (during intravenous infusion), or bradycardia.
- Mouth -Gingival hyperplasia is the most common adverse effect (20%) with long-term use
- Hyperreflexia or hyporeflexia
- Abnormal gait (bradykinesia, truncal ataxia - Ataxia is very typical with elevated phenytoin levels, and may lead to falls and consequent trauma
- Respiratory distress
- Meningeal irritation with pleocytosis
- Tremor (intention)
- Irritability or agitation
- Mental status varies from completely normal to the extremes of stupor and coma, particularly if co-ingestants are present
- Peripheral neuropathy (long-term use)
- Urinary incontinence
- Choreoathetoid movements
- Seizures (rare)
- Death (rare)
- Nystagmus (horizontal, vertical)
- Miosis or mydriasis
- Hypotension, bradycardia , myocardial depression, ventricular fibrillation, asystole, and tissue necrosis all have been associated with the IV formulation.
- Phlebitis, necrosis, even gangrene
- "Purple glove syndrome"
- Distal limb edema, discoloration, and pain after IV administration
- Usually in elderly and after massive/multiple doses
- Right upper quadrant tenderness
- Metabolic - Osteomalacia and hypothyroidism may result from chronic toxicity
Fetal hydantoin syndrome
Intrauterine exposure to phenytoin may result in the following physical features:
- Broad nasal bridge
- Wide fontanelle
- Low hairline
- Cleft lip/palate
- Epicanthal folds
- Short neck
- Low-set ears
- Small or absent nails
- Hip dislocation
- Hypoplasia of distal phalanges
- Impaired growth
- Congenital heart defects
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