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Phenytek (Phenytoin Sodium Extended Release) - Side Effects and Adverse Reactions



Body as a Whole: Allergic reactions in the form of rash and rarely more serious forms (see Skin and Appendages paragraph below) and DRESS (see WARNINGS) have been observed. Anaphylaxis has also been reported.

There have also been reports of coarsening of facial features, systemic lupus erythematosus, periarteritis nodosa and immunoglobulin abnormalities.

Nervous System: The most common adverse reactions encountered with phenytoin therapy are nervous system reactions and are usually dose related. Reactions include nystagmus, ataxia, slurred speech, decreased coordination, somnolence, and mental confusion. Dizziness, vertigo, insomnia, transient nervousness, motor twitchings, paresthesias and headaches have also been observed. There have also been rare reports of phenytoin induced dyskinesias, including chorea, dystonia, tremor and asterixis, similar to those induced by phenothiazine and other neuroleptic drugs.

A predominantly sensory peripheral polyneuropathy has been observed in patients receiving long-term phenytoin therapy.

Digestive System: Acute hepatic failure, toxic hepatitis, liver damage, nausea, vomiting, constipation, enlargement of the lips and gingival hyperplasia.

Skin and Appendages: Dermatological manifestations sometimes accompanied by fever have included scarlatiniform or morbilliform rashes. A morbilliform rash (measles-like) is the most common; other types of dermatitis are seen more rarely. Other more serious forms which may be fatal have included bullous, exfoliative or purpuric dermatitis, Stevens-Johnson Syndrome, and toxic epidermal necrolysis (see WARNINGS). There have also been reports of hypertrichosis.

Hematologic and Lymphatic System: Hematopoietic complications, some fatal, have occasionally been reported in association with administration of phenytoin. These have included thrombocytopenia, leukopenia, granulocytopenia, agranulocytosis, and pancytopenia with or without bone marrow suppression. While macrocytosis and megaloblastic anemia have occurred, these conditions usually respond to folic acid therapy. Lymphadenopathy including benign lymph node hyperplasia, pseudolymphoma, lymphoma, and Hodgkin’s Disease have been reported (see WARNINGS).

Special Senses: Altered taste sensation including metallic taste.

Urogenital:Peyronie’s disease.


Below is a sample of reports where side effects / adverse reactions may be related to Phenytek. The information is not vetted and should not be considered as verified clinical evidence.

Possible Phenytek side effects / adverse reactions in 47 year old male

Reported by a consumer/non-health professional from United States on 2011-10-11

Patient: 47 year old male weighing 70.3 kg (154.7 pounds)

Reactions: Product Substitution Issue, Cervical Vertebral Fracture, Product Measured Potency Issue, Dizziness, Reaction TO Drug Excipients, Toxicity TO Various Agents, Loss of Consciousness

Adverse event resulted in: life threatening event, hospitalization, disablity

Suspect drug(s):

Other drugs received by patient: Phenytek

Possible Phenytek side effects / adverse reactions in 73 year old male

Reported by a health professional (non-physician/pharmacist) from United States on 2012-01-11

Patient: 73 year old male weighing 62.6 kg (137.7 pounds)

Reactions: Anticonvulsant Drug Level Increased, Gait Disturbance, Fall

Suspect drug(s):
    Dosage: 20mg po qd
    Administration route: Oral
    Indication: Major Depression
    Start date: 2010-06-04

    Dosage: 200mg po bid
    Administration route: Oral
    Indication: Convulsion

Possible Phenytek side effects / adverse reactions in 41 year old female

Reported by a pharmacist from United States on 2012-05-31

Patient: 41 year old female

Reactions: Drug Ineffective, Anticonvulsant Drug Level Decreased, Convulsion

Adverse event resulted in: hospitalization

Suspect drug(s):
    Administration route: Oral
    Indication: Convulsion

    Administration route: Oral
    Indication: Convulsion

Other drugs received by patient: Calcium

See index of all Phenytek side effect reports >>

Drug label data at the top of this Page last updated: 2014-05-27

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