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Non-drowsy antihistamines for hay fever

Dr Karen Martin
Reviewed by Dr Karen MartinReviewed on 19.10.2023 | 4 minutes read

Hay fever tablets (also known as antihistamine tablets) are a group of medications that prevent the level of histamine from rising in our body and reduce the symptoms this can cause. Antihistamines can be used to treat a range of conditions including allergic reactions, motion sickness and insomnia. However, the term "antihistamines" most commonly refers to medications that are used to treat hay fever.

There’s an array of hay fever products available and some that are termed non-drowsy and drowsy, so let us take you through where to start and how to identify them.

Doctor’s advice

Who should take hay fever tablets?

If you suffer from hay fever or allergic-type symptoms such as an itchy nose, itchy rash or bite on the skin, or redness and minor skin swelling, then an antihistamine may help relieve these symptoms.

Minor allergic reactions to products (washing detergent, creams, perfume) and food or plant reactions (stinging nettles) can be safely treated with over-the-counter antihistamines. They should get better in hours to days. Make sure to avoid whatever causes the reaction in the future.

If you find that you are getting regular allergic reactions and do not know why, you should discuss it with your doctor, and you may benefit from getting allergy testing.

Non-drowsy antihistamines

Non-drowsy antihistamines, also known as second-generation antihistamines, are a class of medications designed to relieve allergy symptoms without causing significant sedation. These antihistamines block the action of histamine, a chemical released during allergic reactions, and are often preferred for daytime use when alertness is crucial. Some common non-drowsy antihistamines include:

  • Cetirizine (Zyrtec): Effective in relieving allergy symptoms and commonly used for hay fever.

  • Loratadine (Claritin): Similar in efficacy to cetirizine.

  • Fexofenadine (Allegra): Known for its rapid onset of action and greater efficacy against allergic symptoms.

Key differences among non-drowsy antihistamines:

  • Limited sedation: Non-drowsy antihistamines have a reduced ability to cross the blood-brain barrier, resulting in fewer sedative effects compared to their first-generation counterparts.

  • Longer duration of action: They often provide relief for a longer duration, allowing for once-daily dosing in many cases. Both cetirizine and loratadine get to work within 1 to 3 hours, cetirizine perhaps slightly faster, and both peak in effectiveness after 8 to 12 hours, but last for at least 24 hours – loratadine possibly longer. At this dose, they are unlikely to make you drowsy.

  • Suitable for daytime use: Due to their reduced sedative effects, non-drowsy antihistamines are suitable for daytime use and activities that require alertness.

  • Fewer central nervous system side effects: Non-drowsy antihistamines are less likely to cause drowsiness, confusion, or impair cognitive function.

  • May cause a dry mouth or headache: While generally well-tolerated, non-drowsy antihistamines may still have side effects such as dry mouth or headache.

Drowsy antihistamines

Drowsy antihistamines, also known as first-generation antihistamines, are a class of medications that block the action of histamine in the body. However, these medications can also cause drowsiness due to their ability to cross the blood-brain barrier and affect the central nervous system. This may be an advantage if symptoms are worse at night, but not if you need to operate heavy machinery or drive long distances.

Common drowsy antihistamines include:

  • Diphenhydramine: Often used for allergy symptoms, itching, and as a sleep aid.

  • Chlorpheniramine: Used for various allergy symptoms and common cold relief.

  • Hydroxyzine: Used for allergic reactions, itching, and anxiety.

Key differences between drowsy and non drowsy antihistamines

  • Sedation: The primary side effect of drowsy antihistamines is sedation, which can range from mild drowsiness to significant sleepiness.

  • Short duration of action: They often need to be taken multiple times a day due to their shorter duration of action compared to non-drowsy antihistamines. Despite this, some people think they work better for their particular hay fever – it's a question of trial and error what works for you.

  • Caution with activities requiring alertness: Individuals taking drowsy antihistamines should exercise caution when engaging in activities that require alertness, such as driving or operating machinery.

  • Not recommended for long-term use: Due to their sedative effects and the availability of newer, non-drowsy antihistamines, first-generation antihistamines are generally not recommended for long-term use.

  • May cause a dry mouth and constipation: These medications can have side effects such as dry mouth and constipation.

Additionally, individuals with certain medical conditions or those taking other medications should seek advice before using these antihistamines to avoid potential interactions or complications.

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This article has been written by UK-based doctors and pharmacists, so some advice may not apply to US users and some suggested treatments may not be available. For more information, please see our T&Cs.
Dr Karen Martin
Reviewed by Dr Karen Martin
Reviewed on 19.10.2023
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