The inhaler therapy using nebulizer is commonly used for local and systemic drug delivery of drug, through lung is promising now days. Inhalation therapy using nebulizer having several advantages large dose can be administered, quick action, easy and convenient to patient to administer the drug. Nebulizer formulations are known as inhalation suspension or solution, which consists of drug dispersed or solublised in aqueous based formulation containing other excipients. Nebulizer instrument are of three types jet nebulizer, ultrasonic nebulizer and mesh nebulizer. Nebulizer characterization includes delivered dose, aerodynamic particle size distribution, and droplet size distribution, degradation product which determines in-vitro and in-vivo performance. The present overview discusses various features of nebulizers along with its potential advantages, disadvantages and formulation aspects of nebulised drug delivery systems.