Lab testing may show:
Hyperglycemia
Hypokalemia
Hypophosphatemia
The effects are due to the β-agonist effects.  In patients with associated chest pain, a cardiac workup (ECG, and troponin) should be performed.
Clenbuterol toxicity
Infectious
Theophylline toxicity
Sepsis
Nicotine toxicity
Meningitis
Caffeine toxicity
Encephalitis