Dilantin Side Effects
Generic name: phenytoin
Medically reviewed by Drugs.com. Last updated on Jun 23, 2024.
Note: This document contains side effect information about phenytoin. Some dosage forms listed on this page may not apply to the brand name Dilantin.
Applies to phenytoin: injection solution. Other dosage forms:
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 or nurse immediately if any of the following side effects occur while taking phenytoin:
More common
- Chest pain or discomfort
- cold, clammy, or pale skin
- decreased coordination
- difficulty with sleeping
- disorientation
- dizziness
- drowsiness to profound coma
- fainting
- fast, slow, or irregular heartbeat
- hallucination
- headache
- lightheadedness
- measles-like skin rash
- mood or other mental changes
- nausea
- nervousness
- pain in the shoulders, back, neck, or jaw
- shakiness and unsteady walk
- slow heart rate
- slurred speech
- sweating
- swelling of the feet and lower legs
- troubled breathing
- uncontrolled eye movements
- unsteadiness, trembling, or other problems with muscle control or coordination
- unusual tiredness or weakness
Rare
- Bleeding, blistering, burning, coldness, discoloration of the skin, feeling of pressure, hives, infection, inflammation, itching, lumps, numbness, pain, rash, redness, scarring, soreness, stinging, swelling, tenderness, tingling, ulceration, or warmth at the injection site
- blistering, crusting, irritation, itching, peeling, or reddening of the skin
- cracked, dry, or scaly skin
- inability to move the eyes
- increased blinking or spasms of the eyelid
- shakiness in the legs, arms, hands, or feet
- sticking out of the tongue
- trouble with breathing, speaking, or swallowing
- twitching, uncontrolled movements of the tongue, lips, face, neck, trunk, arms, or legs
- unusual facial expressions
Incidence not known
- Abdominal or stomach pain
- bleeding gums
- blisters, hives, or itching
- bloating of the abdomen or stomach
- blood in the urine or stools
- bloody, black, or tarry stools
- blurred vision
- break in the skin, especially associated with blue-black discoloration, swelling, or drainage of fluid
- burning, numbness, tingling, or painful sensations
- chills
- cough or hoarseness
- dark urine
- diarrhea
- dizziness, faintness, or lightheadedness when getting up suddenly from a lying or sitting position
- fainting spells
- fever with or without chills
- general feeling of discomfort or illness
- general feeling of tiredness or weakness
- hair loss
- high fever
- irritation in the mouth
- joint or muscle pain
- light-colored stools
- loss of appetite
- loss of heat from the body
- lower back or side pain
- muscle or joint pain
- painful or difficult urination
- pale skin
- pinpoint red spots on the skin
- red skin lesions, often with a purple center
- red, irritated eyes
- red, swollen skin
- redness and swelling of the gums
- skin rash
- sore throat
- soreness of the muscles
- sores, ulcers, or white spots on the lips or in the mouth
- stomach pain, continuing
- sweating
- swollen glands
- swollen, painful, or tender lymph glands in the neck, armpit, or groin
- unexplained bleeding or bruising
- unsteadiness or awkwardness
- unusual bleeding or bruising
- vomiting
- weakness in the arms, hands, legs, or feet
- weight loss
- yellow eyes or skin
Get emergency help immediately if any of the following symptoms of overdose occur while taking phenytoin:
Symptoms of overdose
- Change in consciousness
- changes in patterns and rhythms of speech
- loss of consciousness
- pounding in the ears
- unusual drowsiness, dullness, tiredness, weakness, or feeling of sluggishness
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:
Incidence not known
- Difficulty having a bowel movement (stool)
- enlarged lips
- feeling of constant movement of self or surroundings
- increased hair growth on the forehead, back, arms, and 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]
More about Dilantin (phenytoin)
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Professional resources
- Dilantin prescribing information
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Other brands
Related treatment guides
References
1. (2001) "Product Information. Dilantin (phenytoin)." Parke-Davis
2. Cerner Multum, Inc. "UK Summary of Product Characteristics."
3. Pharmaceutical Society of Australia (2006) APPGuide online. Australian prescription products guide online. http://www.appco.com.au/appguide/default.asp
Further information
Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.
Some side effects may not be reported. You may report them to the FDA.