How Do Antihistamines Work? 

Dr. Landon Bunderson

PHD, Pollination Ecology

Antihistamines block the effects of histamine, which your body releases when it detects an allergen. 

Histamine is the substance that causes your blood vessels to expand, preparing your body to fight off an infection. Allergens, however, are harmless, which means you suffer the effects of the histamine release for no reason. The effects are what you would expect, sneezing, runny or stuffy nose, red or itchy eyes, even skin rashes. 

It’s a good idea to take an antihistamine before you encounter the allergen. If you have seasonal allergies or are going to be in an area where your allergies will be triggered, take an antihistamine as a preventative measure. 

However,if you have already encountered the allergen and you are suffering from allergy symptoms, an antihistamine can still help to alleviate those symptoms. 

What Are Antihistamines? 

Antihistamines can be purchased over-the-counter or by prescription. They are medicines designed to help relieve allergy symptoms, including things like hay fever, pink eye and hives. They can even help soothe you when you get stung by a bee or bitten by an insect. 

What Types of Antihistamine Are Available? 

There are two main groups of antihistamine. The first type will make you sleepy. The second type are non-drowsy and are designed to be used during the day. 

Antihistamines come in many different forms. You can take them as a liquid, syrup, capsule or tablet, or as a nasal spray. There are also antihistamine eye drops, lotions, and creams.

How Do I Take An Antihistamine?

As with any medicine, you should consult your physician or the pharmacist about how and when to take antihistamines. 

At your consultation, your doctor will ask you to describe your symptoms and will likely give you a medical exam. He or she will then be able to prescribe or recommend the right type of antihistamine and the best form for you and your lifestyle. 

He or she will also explain how to take the medicine, when to take it, how much to take, and for how long you should take it. Your doctor will also explain what to do if you miss a dose or take too much. 

If you suffer from allergies, antihistamines are a tried and true method for alleviating your symptoms.