When you have a cold, you might take a decongestant to help you breathe. Some decongestants contain pseudoephedrine, which mimics the effects of the sympathetic nervous system. What side effects might you expect? Would you expect this medication to make you drowsy?

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.

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