The mixed alpha- and beta blocker labetalol is especially useful for treatment of concomitant tachycardia and hypertension induced by methamphetamine. The phenomenon of "unopposed alpha stimulation" has not been reported with the use of beta blockers for treatment of methamphetamine toxicity. Other appropriate antihypertensive drugs to administer during hypertensive crisis resulting from stimulant overdose are vasodilators such as nitroglycerin, diuretics such as furosemide, and alpha blockers such as phentolamine. Contraindications
Contraindications for beta blockers include:

Asthma
The 2007 National Heart, Lung, and Blood Institute (NHLBI) asthma guidelines recommend against the use of non-selective beta blockers in asthmatics, while allowing for the use of cardio selective beta blockers. : 182 Cardio selective beta blocker (β1 blockers), if really required, can be prescribed at the least possible dose to those with mild to moderate respiratory symptoms. β2-agonists can somewhat mitigate β-Blocker-induced bronchospasm where it exerts greater efficacy on reversing selective β-blocker-induced bronchospasm than the nonselective β-blocker-induced worsening asthma and/or COPD. Diabetes mellitus
Epinephrine signals early warning of the upcoming hypoglycemia.Beta blockers inhibition on epinephrines effect can somewhat exacerbate hypoglycemia by interfering with glycogenolysis and mask signs of hypoglycemia such as tachycardia, palpitations, diaphoresis, and tremors. Diligent blood glucose level monitoring is necessary for a patient with diabetes mellitus on beta blocker. Hyperthyroidism
Abrupt withdrawal can result in a thyroid storm. Bradycardia or AV block
Unless a pacemaker is present, beta blockers can severely depress conduction in the AV node, resulting in a reduction of heart rate and cardiac output.
The physiological symptoms of the fight-or-flight response (pounding heart, cold/clammy hands, increased respiration, sweating, etc.) are significantly reduced, thus enabling anxious individuals to concentrate on the task at hand. Musicians, public speakers, actors, and professional dancers have been known to use beta blockers to avoid performance anxiety, stage fright, and tremor during both auditions and public performances. The application to stage fright was first recognized in The Lancet in 1976, and by 1987, a survey conducted by the International Conference of Symphony Orchestra Musicians, representing the 51 largest orchestras in the United States, revealed 27% of its musicians had used beta blockers and 70% obtained them from friends, not physicians. Beta blockers are inexpensive, said to be relatively safe, and on one hand, seem to improve musicians performances on a technical level, while some, such as Barry Green, the author of "The Inner Game of Music" and Don Greene, a former Olympic diving coach who teaches Juilliard students to overcome their stage fright naturally, say the performances may be perceived as "soulless and inauthentic". Surgery
Low certainty evidence indicates that the use of beta blockers around the time of cardiac surgery may decrease the risk of heart dysrhythmias and atrial fibrillation. Starting them around the time of other types of surgery, however, may worsen outcomes. For non-cardiac surgery, the use of beta blockers to prevent adverse effects may reduce the risk of atrial fibrillation and myocardial infarctions (very low certainty evidence), however, there is moderate certainty evidence that this approach may increase the risk of hypotension.