Answer:
These drugs, like sympathetic nervous system, narrows blood vessels.since congestion is caused by dilation of blood vessels., Therefore they reduces bloods flow and possible swelling and congestion through contrition of blood vessels .They should therefore work like Adrenalin -fight or flight action. consequently the side effects are;
, headache, tachycardia,changes in the mental and mood changes,and tremor, insomnia. Which are due to narrowing of blood flow.
Yes,they lead to drowsiness due to the vasoconstriction.
