By Dr Ananya Mandal, MD
The various effects of beta blocker therapy on different parts of the body can lead to patients experiencing several side effects.
Some examples of these side effects include:
Slowed heart rate
Beta blockers that target the beta 1 receptor prevent stimulation of the heart activity by stress hormones. Sometimes, the heart rate can become too slow and lead to the patient feeling dizzy and faint. The slowing of heart rate is usually brought about by the effect on the sino-atrial node, which generates the impulses that cause the heart to beat.
Beta blockers can cause constriction of the small blood vessels and lead to a reduction in the amount of blood that is circulated to the peripheries such as the hands and feet.
Aggravation of asthma
Blocking of the beta 2 receptors in the bronchioles can lead to constriction of the airways and patients with asthma or chronic obstructive pulmonary disease (COPD) are advised not to take beta blockers.
Sleeping and emotional difficulties
Beta blocker therapy can lead to fatigue, depression, vivid dreams, nightmares and impotence in some individuals.
Risks in diabetes
If blood sugar drops severely (hypoglycaemia) in diabetic individuals, symptoms occur that can act as warning signs such as palpitations, increased heart rate and sweating. However, if a diabetic individual is taking beta blocker therapy, these symptoms are masked, meaning patients may not be alerted to their low blood sugar level.
Risk of diabetes
Some research suggests that beta blockers raise blood sugar levels and that the therapy can increase the likelihood of diabetes developing.
Reviewed by Sally Robertson, BSc
Last Updated: Feb 13, 2014