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Tonocard Side Effects

Generic name: tocainide

Medically reviewed by Last updated on Sep 30, 2023.

Note: This document contains side effect information about tocainide. Some dosage forms listed on this page may not apply to the brand name Tonocard.

Applies to tocainide: oral tablet.


Call your doctor immediately if you experience wheezing, coughing, difficulty breathing, chest pain, chest discomfort, worsening irregular heartbeats, a fever, a sore throat, a throat infection, a sore mouth, mouth ulcers, a rash, or unusual bruising or bleeding.

Do not skip doses or change your dosing schedule without talking to your doctor. Changing your schedule could make your condition much worse.

Use caution when driving, operating machinery, or performing other hazardous activities. Tocainide may cause dizziness, drowsiness, or blurred vision. If you experience dizziness, drowsiness, or blurred vision, avoid these activities.

If you experience any of the following serious side effects, stop taking tocainide (the active ingredient contained in Tonocard) and seek emergency medical attention:

Other, less serious side effects may be more likely to occur. Continue to take tocainide and talk to your doctor if you experience

Side effects other than those listed here may also occur. Talk to your doctor about any side effect that seems unusual or that is especially bothersome.

For Healthcare Professionals

Applies to tocainide: oral tablet.


Tocainide is generally well tolerated. Minor, transient, dose-dependent side effects have occurred frequently (up to 80%) and usually involved nervous system or gastrointestinal symptoms. Approximately 21% of patients discontinued tocainide (the active ingredient contained in Tonocard) because of adverse effects. The incidence of side effects increased when plasma tocainide concentrations exceeded 10 mcg/mL. Tremor may indicate that the maximum dosage is being approached.

General adverse reactions affecting the body as a whole included fatigue (0.8% to 1.6%) and hot or cold sensations (0.5% to 1.5%). Cinchonism, asthenia, and malaise have been reported in less than 1% of patients.[Ref]


Gastrointestinal side effects are the most frequently observed. Nausea, vomiting, and anorexia have occurred in 15% to 35% of patients. Dosage reductions or administration with food, which will not affect tocainide (the active ingredient contained in Tonocard) plasma concentrations, helps minimize these side effects. Diarrhea has been reported in 6.8% of patients. Pancreatitis, abdominal discomfort, constipation, dysphagia, stomatitis, taste alteration, dry mouth and thirst were reported in less than 1% of patients.[Ref]

Nervous system

Nervous system side effects have occurred in 15% to 25% of patients on chronic therapy. Lightheadedness/dizziness/vertigo (8% to 25.3%), tremors (2.9% to 21.6%), paresthesia (3.5% to 9.2%), coordination difficulties (1.2%), and headache (2.1% to 4.6%) have been reported. Neurologic side effects are usually dose-related and resolve with dosage reductions. Adverse effects such as coma, seizures, myasthenia gravis, dysarthria, decreased mental acuity/impaired memory, increased stuttering/slurred speech, and local anesthesia have been reported in less than 1% of patients.[Ref]

Tocainide, like lidocaine, crosses the blood-brain barrier and may produce neurotoxicity, including seizures. Tremor and paresthesias indicate a maximum tolerable dosage.[Ref]


Cardiovascular side effects such as exacerbation of old or induction of new arrhythmias, including ventricular tachycardia or fibrillation, have occurred in 16% of patients. Although tocainide (the active ingredient contained in Tonocard) has a minimal effect on the sinus node, cases of sinus arrest and SA block have been reported, particularly in patients with sick sinus syndrome. Exacerbation of congestive heart failure occurred in 1% to 5% of patients. Bradycardia (1.8%), hypotension (3.4%), and chest pain (1.6%) have been reported. Angina, hypertension, claudication, increased QRS duration, extension of acute myocardial infarction, vaso-vagal episodes, syncope, and edema have occurred.[Ref]


Hematologic side effects of tocainide (the active ingredient contained in Tonocard) have been rare (0.2% of patients), but serious reactions and death have occurred. Aplastic anemia and agranulocytosis have been associated with tocainide, some were irreversible and resulted in death. Weekly complete blood count analysis is recommended during the first three months of therapy and monthly, thereafter. Bone marrow depression and granuloma, hemolytic anemia, anemia, leukopenia, neutropenia, thrombocytopenia, and eosinophilia have been associated with tocainide therapy in less in 1% of patients. Septicemia and septic shock have been reported.[Ref]

Tocainide-associated blood dyscrasias have been reported most often during the first 2 to 12 weeks of therapy.[Ref]


Hypersensitivity reactions manifesting as rash, fever, joint pain, eosinophilia, or abnormal liver function tests have been reported in up to 25% of patients. Stevens-Johnson syndrome has been associated with tocainide (the active ingredient contained in Tonocard) Interstitial pneumonitis is a rare side effect of tocainide and may be initiated by a hypersensitivity mechanism.[Ref]


Dermatologic side effects occurred in 12% to 28% of patients. Serious reactions have included Stevens-Johnson syndrome, erythema multiforme, rash with stomatitis, or rash requiring or prolonging hospitalization. Overall, the incidence of serious skin reactions is 0.5 to 3.8 per 100,000 prescriptions of tocainide (the active ingredient contained in Tonocard) with fatalities in 0.9 per 100,000 prescriptions. Diaphoresis has been reported in up to 8.3% of patients.[Ref]

Data from 21 reports of severe skin reactions between 1985 to 1986, indicated 67% of the reactions occurred during the first 3 weeks of therapy.[Ref]


Psychiatric side effects have included confusion/disorientation/hallucinations (2.1% to 11.2%), altered mood/awareness (1.5% to 11%), nervousness (11.5%), and anxiety (1.1% to 1.5%). Psychosis/disturbances, depression, agitation, insomnia/sleep disturbances, and dream abnormalities have been reported in less than 1% of patients.[Ref]


Respiratory side effects, although rare, have resulted in death. Tocainide-associated pulmonary fibrosis has occurred, most often in seriously ill patients. Symptoms of dyspnea and cough usually presented within 3 to 18 weeks of initiation of therapy. Interstitial infiltrates were seen on radiologic examination. Respiratory arrest, pulmonary edema, fibrosing alveolitis, pneumonia, interstitial pneumonitis (0.03%), dyspnea, hiccough, yawning, and smell alterations have been reported in less than 1% of patients.[Ref]

Evidence of a hypersensitivity mechanism has been reported for tocainide-associated pulmonary fibrosis.[Ref]


Hepatic side effects usually have been mild and transient, manifesting as slightly elevated liver function tests. Hepatitis and jaundice have been reported in less than 1% of patients.[Ref]


Immunologic and clinical changes consistent with a lupus-like syndrome have been reported.[Ref]

A 75-year-old man with a history of coronary artery bypass grafting and short runs of ventricular tachycardia was given tocainide 400 mg every 8 hours. Three weeks after initiation of therapy he developed unexplained malaise, chills, sweats, and fever and was given oral antibiotics. His physical exam was noncontributory; laboratory tests revealed a white blood cell count of 4,400/mm3. An evaluation of typical and atypical infectious pathogens was negative. A CT scan noted a right pleural effusion and hepatosplenomegaly. Bone marrow aspiration revealed numerous noncaseating granuloma, decreased iron stores, and 30% cellularity. A serum ANA was positive at 1:640 (speckled pattern). Resolution of all symptoms occurred within one week of discontinuing tocainide. Rechallenge was not attempted.[Ref]


Musculoskeletal side effects such as arthritis/arthralgia (4.7%) and myalgia (1.7%), and ataxia (02.% to 10.8%) have been reported. Side effects occurring in less than 1% of patients included muscle cramps/twitches/spasms, neck pain or pain radiating from the neck, and shoulder pressure.[Ref]


Ocular disturbances have included blurred vision in up to 10% of patients. Nystagmus occurred less frequently (1.1%).[Ref]


Ototoxicity characterized by vertigo and tinnitus/hearing loss has occurred in 25.3% and 1.1% of patients, respectively. Rare incidences of earache have been reported.[Ref]


Genitourinary side effects including urinary retention, polyuria, and increased diuresis have occurred in less than 1% of patients.[Ref]


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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.