Note: This document contains side effect information about phenytoin. Some dosage forms listed on this page may not apply to the brand name Dilantin.
Summary
Common side effects of Dilantin include: congenital anomalies. Other side effects include: hepatic necrosis, ataxia, confusion, constipation, depression, dizziness, drowsiness, fatigue, hypertrichosis, mental status changes, myasthenia, nervousness, numbness, tremor, tremor of hands, vertigo, excitement, irritability, mood changes, and restlessness. Continue reading for a comprehensive list of adverse effects.
Applies to phenytoin: oral capsule extended release, oral suspension, oral tablet chewable. Other dosage forms:
- injection solution
Serious side effects of Dilantin
Along with its needed effects, phenytoin (the active ingredient contained in Dilantin) may cause some unwanted effects. Although not all of these side effects may occur, if they do occur they may need medical attention.
Check with your doctor immediately if any of the following side effects occur while taking phenytoin:
More common
- Decreased coordination
- mental confusion
- nervousness
- slurred speech
- trouble with breathing, speaking, or swallowing
- unsteadiness, trembling, or other problems with muscle control or coordination
Rare
- Inability to move the eyes
- increased blinking or spasms of the eyelid
- shakiness and unsteady walk
- shakiness in the legs, arms, hands, or feet
- sticking out of the tongue
- trembling or shaking of the hands or feet
- twitching, twisting, or uncontrolled repetitive movements of the tongue, lips, face, arms, or legs
- uncontrolled twisting movements of the neck, trunk, arms, or legs
- unusual facial expressions
Incidence not known
- Bleeding gums
- blistering, peeling, or loosening of the skin
- blisters, hives, itching, skin rash
- bloating of the abdomen or stomach
- blood in the urine or stools
- bloody, black, or tarry stools
- chest pain or discomfort
- chills
- cough
- dark urine
- diarrhea
- difficulty with moving
- fainting spells
- fever with or without chills
- general feeling of discomfort or illness
- hair loss
- headache
- high fever
- hoarseness
- irritation in the mouth
- joint or muscle pain
- light-colored stools
- lightheadedness or dizziness
- lower back or side pain
- muscle stiffness
- nausea
- numbness, tingling, or pain in the hands or feet
- painful or difficult urination
- pale skin
- pinpoint red spots on the skin
- red skin lesions, often with a purple center
- red, irritated eyes
- redness and swelling of the gums
- slow or irregular heartbeat
- sore throat
- sores, ulcers, or white spots on the lips or in the mouth
- stomach pain
- swollen, painful, or tender lymph glands in the neck, armpit, or groin
- unusual bleeding or bruising
- unusual tiredness or weakness
- upper right abdominal or stomach pain
- vomiting
- weight loss
- yellow eyes or skin
Other side effects of Dilantin
Some side effects of phenytoin may occur that usually do not need medical attention. These side effects may go away during treatment as your body adjusts to the medicine. Also, your health care professional may be able to tell you about ways to prevent or reduce some of these side effects.
Check with your health care professional if any of the following side effects continue or are bothersome or if you have any questions about them:
More common
- Trouble sleeping
- uncontrolled eye movements
Incidence not known
- Difficulty having a bowel movement
- enlarged lips
- feeling of constant movement of self or surroundings
- increased hair growth on the forehead, back, arms, or legs
- pain of the penis on erection
- sensation of spinning
For Healthcare Professionals
Applies to phenytoin: compounding powder, injectable solution, oral capsule, oral capsule extended release, oral suspension, oral tablet chewable.
Cardiovascular
Common (1% to 10%): Hypotension, vasodilation, tachycardia
Uncommon (0.1% to 1%): Shock, cardiac arrest, syncope, cerebral hemorrhage, palpitation, sinus bradycardia, atrial flutter, bundle branch block, cardiomegaly, cerebral infarct, postural hypotension, pulmonary embolus, QT interval prolongation, thrombophlebitis, ventricular extrasystoles, congestive heart failure
Frequency not reported: Cardiovascular collapse, severe cardiotoxic reactions with atrial and ventricular conduction depression (including bradycardia and all degrees of heart block), asystole ventricular fibrillation, periarteritis nodosa[Ref]
Dermatologic
Very common (10% or more): Rash (more serious and rare forms have included bullous, exfoliative or purpuric dermatitis, lupus erythematosus, Stevens-Johnson syndrome and toxic epidermal necrolysis), pruritus
Common (1% to 10%): Maculopapular rash, urticaria, sweating, skin discoloration, contact dermatitis, pustular rash, skin nodule, ecchymosis
Frequency not reported: Hirsutism, hypertrichosis, coarsening of the facial features, enlargement of the lips, Peyronie's disease. Dupuytren's contracture and drug rash with eosinophilia and systemic symptoms (DRESS), erythema multiforme, SJS/TEN risk in patients of Asian ancestry who have HLA-B 1502[Ref]
Endocrine
Frequency not reported: Decreased serum T4 and FT4, increased serum estradiol levels, gynecomastia, alterations in vitamin D metabolism[Ref]
Gastrointestinal
Very common (10% or more): Nausea (13%)
Common (1% to 10%): Tongue disorder, dry mouth, vomiting, constipation
Uncommon (0.1% to 1%): Dyspepsia, diarrhea, anorexia, GI hemorrhage, increased salivation, tenesmus, tongue edema, dysphagia, flatulence, gastritis, ileus
Frequency not reported: Hypoesthesia of the tongue, gingival hyperplasia[Ref]
Genitourinary
Uncommon (0.1% to 1%): Urinary retention, oliguria, dysuria, vaginitis, albuminuria, genital edema, polyuria, urethral pain, urinary incontinence, vaginal moniliasis
Frequency not reported: Feeling of warmth or tingling in the groin, Peyronie's disease[Ref]
Hematologic
Common (1% to 10%): Ecchymosis
Uncommon (0.1% to 1%): Thrombocytopenia, anemia, leukocytosis, cyanosis, hypochromic anemia, leukopenia, lymphadenopathy, petechia
Frequency not reported: Granulocytopenia, agranulocytosis, pancytopenia (with or without bone marrow suppression), aplastic anemia[Ref]
Hepatic
Uncommon (0.1% to 1%): Liver function tests abnormal, kidney failure
Frequency not reported: Toxic hepatitis, hepatocellular damage[Ref]
Hypersensitivity
Frequency not reported: Hypersensitivity syndrome, periarteritis nodosa
Postmarketing reports: Anaphylactoid reaction, anaphylaxis[Ref]
Immunologic
Uncommon (0.1% to 1%): Sepsis, flu syndrome, cryptococcosis
Frequency not reported: Immunoglobulin abnormalities[Ref]
Local
Common (1% to 10%): Injection site reaction, injection site pain
Uncommon (0.1% to 1%): Injection site inflammation, injection site edema, injection site hemorrhage[Ref]
Metabolic
Uncommon (0.1% to 1%): Generalized edema, cachexia, diabetes insipidus
Frequency not reported: Hyperglycemia, appetite disorder, hypokalemia[Ref]
Musculoskeletal
Common (1% to 10%): Back pain, chills, myasthenia
Uncommon (0.1% to 1%): Myopathy, leg cramps, arthralgia, myalgia, muscular weakness, muscle twitching, muscle spasms
Frequency not reported: Systemic lupus erythematosus, polyarthritis, Purple Glove Syndrome[Ref]
Nervous system
Very common (10% or more): Nystagmus (59%), dizziness (31%), somnolence (27%), ataxia (18%)
Common (1% to 10%): Headache, stupor, incoordination, paresthesia, extrapyramidal syndrome, tremor, vertigo, brain edema, tinnitus, taste perversion (including metallic taste), taste loss, reflexes decreased, reflexes increased, migraine, slurred speech, dysarthria, intracranial hypertension, hyperesthesia, hyporeflexia
Uncommon (0.1% to 1%): Twitching, Babinski sign positive, circumoral paresthesia, hemiplegia, hypotonia, convulsion, meningitis, CNS depression, hypokinesia, hyperkinesia, brain edema, paralysis, aphasia, coma, myoclonus, acute brain syndrome, encephalitis, subdural hematoma, encephalopathy, akathisia
Frequency not reported: CNS depression, dyskinesia (including chorea), dystonia and asterixis similar to those induced by phenothiazines or other neuroleptic drugs, drowsiness, motor twitching, tonic seizures, sensory peripheral polyneuropathy (in patients receiving long-term therapy)[Ref]
Ocular
Common (1% to 10%): Diplopia, amblyopia, blurred vision, visual impairment
Uncommon (0.1% to 1%): Photosensitivity reaction, photophobia, eye pain, mydriasis, visual field defect[Ref]
Other
Common (1% to 10%): Asthenia, deafness, accidental injury, fever, face edema, hyperacusis, parosmia, ear pain
Uncommon (0.1% to 1%): Malaise[Ref]
Renal
Common (1% to 10%): Pelvic pain
Uncommon (0.1% to 1%): Kidney failure[Ref]
Respiratory
Common (1% to 10%): Pneumonia
Uncommon (0.1% to 1%): Pharyngitis, sinusitis, hyperventilation, rhinitis, apnea, aspiration pneumonia, asthma, dyspnea, atelectasis, cough increased, sputum increased, epistaxis, hypoxia, pneumothorax, hemoptysis, bronchitis
Postmarketing reports: Respiratory arrest (sometimes fatal)[Ref]
Psychiatric
Common (1% to 10%): Agitation, thinking abnormal, nervousness, depression
Uncommon (0.1% to 1%): Confusion, insomnia, depersonalization, psychosis, emotional lability, personality disorder, hostility, amnesia, neurosis, euphoric mood[Ref]