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Dandelion Fields

How Antihistimanes Work

Antihistamines block the effects of a substance call histamine that occurs naturally in your body.

Antihistamines block the effects of a substance called histamine in your body

Your body releases histamine when it detects something harmful, such as an infection. Histamine causes blood vessels to expand and the skin to swell, which helps protect the body. If you have allergies, your body can mistake something harmless for a threat and produce histamine.


The histamine causes an allergic reaction with itchy, watery eyes, a running or blocked nose, sneezing and rashes.


Antihistamines help stop this from happening if you take them before you come into contact with the substance you're allergic to. Or they can reduce the severity of symptoms if you take them afterwards.

How antihistamines work

Can everyone take Antihistamines?

Most people can safely take antihistamines. But not all antihistamines are suitable for everyone.  Talk to a pharmacist or GP for advice if you are:

 - pregnant

 - trying to get pregnant

 - breastfeeding

 - taking other medicines

or have an underlying health condition, such as heart disease, liver disease, kidney disease or epilepsy


Read the label/leaflet that comes with your medicine to check it's safe for you to take.

How long should I take Antihistamines for?

The duration of treatment depends on the type, duration and course of your complaints. Please ask your doctor or pharmacist for advice.

And, as with all medicines, always read the label. 

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