Silicon-based MHz ultrasonic multiple Fourier horns in resonance are capable of producing high-throughput micrometer-sized droplets at low drive power. The centimeter-sized nozzles together with low power requirement enabled most recent realization of the first pocket-sized ultrasonic nebulizer (8.6 × 5.6 × 1.5 cm3) that contains nozzle, IC electronic driver, cell-phone battery, micro pump, drug reservoir, and liquid feed. A variety of common drugs for asthma, chronic obstructive pulmonary disease (COPD), diabetics, cyanide poisoning, pulmonary fibrosis, etc. such as albuterol, Humulin U-100, cobinamide, interferon-γ, and budesonide suspension have been nebulized with desirable aerosol size and throughput. © 2013 IEEE.