Hay Fever & Antihistamines

If you’re one of the many thousands of Australians who suffer from hay fever, Spring can be a real nightmare. On the frontline of treatment options are Antihistamines. These are medications that work by blocking or reducing a chemical called histamine.

When you have an allergic reaction to something like pollen or pet hair, your body's immune system releases histamine. They bind to receptors in your body, often causing symptoms such as sneezing and itching. In fact, histamines play a role in a number of body processes that include:

• Widens blood vessels (vasodilation).

• Help fluids move through blood vessel walls.

• Inflammation.

• Affect muscle contractions in your intestines and lungs.

• Stimulate stomach (gastric) acid secretion.

• Affect your heart rate.

• Help transmit messages between nerve cells.

As well as sneezing and itching, the release of histamines can also cause other allergy symptoms, like:

• Nasal congestion or runny nose.

• Hives and other skin rashes.

• Watery eyes.

2 Different Types of Antihistamines

1. Sedating (First-Generation) Antihistamines: 

These can cause drowsiness, dry mouth, and affect coordination. Examples include promethazine (Phenergan) and diphenhydramine (Benadryl).

2. Non-Sedating (Second-Generation) Antihistamines: 

These are less likely to cause sleepiness and have fewer side effects. Examples include loratadine (Claratyne), cetirizine (Zyrtec), and fexofenadine (Telfast).

Important Facts About Antihistamines

• Antihistamines can be taken daily to manage symptoms or only when symptoms appear. 

• Side effects of sedating antihistamines can include drowsiness, dry mouth, and blurred vision. 

• Second-generation antihistamines are generally safer for daily use as they cause less drowsiness. 

• Antihistamines are not recommended for treating anaphylaxis (severe allergic reactions). Adrenaline (epinephrine) is the essential treatment for anaphylaxis. 

• Antihistamines don’t always completely control symptoms. This is because other chemicals besides histamine may be partly responsible for the symptoms.

Many antihistamines are available over the counter from your local pharmacy, and they come in many forms - pills, liquids, eye drops, and nasal sprays.

We recommend that you discuss your symptoms with a pharmacist before buying/taking/using an antihistamine medication.

Always follow the instructions on the box or packaging.

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