Ingestion of large doses of the active ingredients has been reported to cause the following effects: gastrointestinal disturbances such as abdominal pain, nausea, vomiting and diarrhoea would be expected to occur with the menthol and squill.
Common symptoms of digoxin overdosage include headache, facial pain, fatigue, weakness, dizziness, drowsiness, disorientation, mental confusion, bad dreams and more rarely delirium, acute psychoses, and hallucinations. Convulsions have been reported. Visual disturbances including blurred vision may occur. Colour vision may be affected with objects appearing yellow or less frequently green, red, brown, blue or white.
Adverse effects on the heart may result from the cardiac glycosides in squill. Toxic doses may cause or aggravate heart failure. Supraventricular or ventricular arrhythmias and defects of conduction are common and may be an early indication of excessive dosage.
In addition CNS effects such as vertigo, ataxia and drowsiness have been reported after ingestion of large quantities of menthol; reported adverse effects following excessive ingestion of liquorice include hypertension, congestive heart failure, cardiac arrest, headache, muscle weakness, myopathy, myoglobinuria, paralysis, hyperprolactinaemia and amenorrhoea. In the unlikely event of overdosage with this preparation, gastric lavage and / or symptomatic treatment together with supportive measures should be employed.
Treatment of acute digoxin poisoning consists of emptying the stomach by emesis or lavage. Activated charcoal may be given. Cardiac toxicity should be treated under ECG control and serum electrolytes should be monitored. Anti-arrhythmic treatment may be necessary and should be determined by the specific arrhythmia present. Atropine may be given intravenously to control bradycardia and in patients with heart block; cardiac pacing may be necessary if atropine is not effective. Cholestyramine or colestipol may be of use in increasing the elimination of cardiac glycosides.