Objectives: This paper provides a study on some of the existing approaches that attempt to provide congestion adaptive routing in mobile ad hoc network. Findings: Mobile ad hoc network is a type of multi hop wireless network formed instantly without any fixed infrastructure using mobile nodes. Nodes in these networks are highly mobile means that they can move freely and randomly at any speed in any direction without any assistance. The mobility of nodes can cause frequent changes in the network topology which in turns leads to frequent path breaks which severely affects the performance of the network. Another prominent factor which affects the performance of a mobile ad hoc network is congestion. Congestion can occur at any intermediate nodes at any time due to excessive incoming traffic as well as lack of network resources such as bandwidth,energy,lack of physical security,memory and so on. Upon congestion the nodes drops the packets which in turn affects the receiver throughput. Conclusion: Dealing with congestion in such network in a reactive manner creates long delays,high packet losses and waste of resources. Over the decades many routing algorithms have been proposed by the research community but only few protocols address the congestion phenomena. This paper provides a detailed study on congestion issues in MANETs and some of the existing approaches. © 2016,International Journal of Pharmacy and Technology. All rights reserved.