What’s the difference between antihistamines and decongestants?


What’s the difference between antihistamines and decongestants?

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People sometimes (inaccurately) use them interchangeably but antihistamines are specifically for allergies. Histamines are compounds related to immune system response, and allergies are caused by hypersensitivity of the immune system.

Decongestants are just drugs that treat nasal congestion in the upper respiratory tract, which might be caused by allergies but could be lots of other things too.

If you just look at the labels on the drugs, you’ll see the active ingredients are different. Some products might be a combination of the two, but it’s just two different drugs mixed together.


Think of it like having a sibling trying to enter the room hellbent on releasing stinkbugs.

Antihistimines are like you blocking the door so said sibling doesn’t unleash the stink.

Decongestants is you spraying Febreeze after he got in so you can combat the after effects.

One medicine takes time to reduce the cause of a congested state. The other is a quick fix to offer relief of congestion yet does nothing to prevent it in 6-12 hours. If the antihistamine is given enough time (3-4 days), the decongestant will not be needed. *Edit: When related to allergies which I presume is why you’re asking. You wouldn’t take Claritin for a common cold as an example.

antihistamines usually belong to a class of drugs known as anticholinergics.

these drugs slow your body down by making it so that your body cant use acetylcholine and histamine. histamine is what makes you have allergic reactions, so by blocking histamine, it blocks your ability to get allergy symptoms.

decongestants are usually adrenergic agonists. this means they simulate adrenaline when in the body and speed the body up. they cause your blood vessels to constrict, which in the nose, drains it out better.