Adverse reactions/toxicity are uncommon at serum theophylline levels <20 mcg/mL. The most consistent adverse reactions are due to overdosages.
Gastrointestinal: Nausea, vomiting, epigastric pain, diarrhoea.
Central Nervous System: Headache, irritability, insomnia, muscle twitching, clonic and tonic generalized convulsions.
Cardiovascular System: Palpitation, tachycardia, extrasystoles, flushing, hypotension, ventricular arrhythmias.
Renal: Potentiation of diuresis.
Others: Alopecia, rash.
Salbutamol is generally well tolerated and serious toxic effects are few. The adverse reactions to salbutamol are similar in nature to reactions to other sympathomimetic agents, although the incidence of certain cardiovascular effects is lower with salbutamol. The most frequent adverse reactions to salbutamol are nervousness and tremor. Other reported reactions are headache, tachycardia and palpitations, muscle cramps, insomnia, nausea, weakness and dizziness. Rare cases of urticaria, angioedema, rash and oropharyngeal edema have been reported after the use of salbutamol. The reactions are generally transient in nature and it is usually not necessary to discontinue treatment with salbutamol.