Especially at the start of therapy, CNS disturbances such as fatigue, dizziness, depressive moods, lightheadedness, light headache, sweating, sleep disturbances, increased dream activity and hallucinations may occur. These symptoms are normally mild and reversible.
Occasionally temporary gastro-intestinal problems such as nausea, vomiting, abdominal pains, constipation or diarrhoea may occur. Dyspnoea may occur on exertion, rarely bronchial spasms (see Contraindications).
Occasionally, there might be a tingling sensation and a feeling of coldness in the extremities, and rarely, muscle weakness of muscle cramps. Increased discomfort has been observed in patients with intermittent claudication or with angiospasms in toes and fingers (Raynaud's disease).
In rare cases, there may be an increased fall in blood pressure, including on transition from prone to standing positions (orthostatic hypotension) occasionally with unconsciousness, drop in pulse rate, atrioventricular conduction disturbances, increased myocardial insufficiency with peripheral oedema (fluid collection), cardialgia and palpitations.
Rarely to be reckoned with are dryness of the mouth, conjunctivitis, and lessened tear flow (contact lens wearers should pay attention to this).
In individual cases there may be libido and potency disturbances, weight gain, sensitivity to light with the appearance of skin rashes after exposure to light, as well as hair loss, impaired vision, or tinnitus.
In addition, hypersensitivity reactions such as itching, reddening of the skin, skin rash (e.g. dystrophic skin lesions) may occur, and in individual cases changes in hepatic function values, hepatitis, arthritis, a drop on blood platelets (thrombocytopenia) or in leucocytes (leucopenia), allergic coryza or plastic induration of the penis (Peyronie's disease).
An increase (up to gangrenous stages) of existing peripheral circulatory disturbances as well as personality changes (such as mood swings, short-term memory loss) have been described.
In individual cases, beta-receptor blockers can release a psoriasis, make the symptoms of the illness worse or lead to psoriasiform skin eruptions.
Notes: In rare cases, latent diabetes mellitus may appear or an existing condition may worsen; symptoms of lowered blood sugar (e.g. rapid pulse) may be masked.
Patients receiving beta-blockers display a severe form of anaphylactic shock. Treatment of hypertension with this medicine requires regular medical control.