What Are The Strongest Antihistamines?

If you’re struggling with hay fever, finding the right antihistamine can make all the difference. Yet, with so many options available, it can be difficult to know which one is the best or strongest.

In this article, we explore how antihistamines work, the different types available, the strongest over-the-counter antihistamines, and the most potent prescription treatments. We’ll also discuss which types might work best for different allergies, compare the potential side effects, and address some of the most frequently asked questions.

Antihistamines are medications taken to relieve allergy symptoms. They work by blocking the effects of histamine, a chemical your immune system produces in response to an allergen, resulting in an allergic reaction. By stopping histamine from binding to its receptors, antihistamines can relieve common symptoms, such as sneezing, watery eyes, itching, and skin rashes.

There are 2 main antihistamine categories: first generation (sedating) and second generation (non-sedating). The main differences between them are how likely they are to make you drowsy and also the likelihood of causing side effects.

First generation antihistamines

Also known as sedating antihistamines, these are older medications that cross the blood-brain barrier easily, causing drowsiness. They are useful if taken at night or if your sleep is disturbed by allergy symptoms.

Common examples of first-generation antihistamines include:

• chlorphenamine
• hydroxyzine
• diphenhydramine

Second generation antihistamines

Second-generation antihistamines are a newer type of medication that are designed to minimise drowsiness while effectively relieving allergy symptoms. They are a suitable and preferred option for daytime use. Common examples include:

• loratadine
• cetirizine
• fexofenadine
• deloratadine

Because second-generation antihistamines do not cross the blood-brain barrier as easily, they generally cause fewer side effects.

Different antihistamine forms

Antihistamines are also available in a variety of forms to suit your needs and preferences, including:

• tablets
• capsules
• nasal sprays
• syrups and liquids
• creams and lotions
• eye drops

Tablets and capsules are the most common antihistamine forms and are easily taken with a glass of water. Syrups and liquids, on the other hand, are often preferred by children or people who have difficulty swallowing pills.

Topical forms like nasal sprays, lotions, and eye drops can be used to treat allergy symptoms affecting that area. For example, if you have watery, itchy eyes, you may choose eye drops, or if you need to relieve nasal congestion, nasal sprays are a useful option.

The strongest antihistamines available in the UK tend to be prescription-only and are given to treat moderate to severe allergy symptoms. How potent an antihistamine is can be determined by its dose, how quickly it starts to work, and how long it provides relief.

1. Fexofenadine (Telfast)

When prescribed at the higher dose of 180mg, fexofenadine is considered one of the strongest antihistamines available in the UK and can control symptoms for up to 24 hours per dose.

2. Desloratadine 5mg tablets (Neoclarityn)

This is also a potent prescription-only medication that can effectively treat hay fever and other allergy symptoms.

If you’re looking for the strongest over-the-counter antihistamine, cetirizine is a popular option that does not need a prescription. It starts to work within 30 minutes and can last for 24 hours.

Choosing the right antihistamine for your needs is dependent on your specific situation. For example, you’ll need to consider your symptoms, daily activities, and any other health conditions or medications you are taking before taking antihistamines for hay fever. Here are some things to think about:

• symptom severity – the more severe your symptoms are, the stronger the antihistamine you’ll need
• duration of symptoms – depending on how long your symptoms last, you may need long-lasting medications
• medical conditions – things like pregnancy can narrow the list of appropriate antihistamine medications, so it’s important to speak to your doctor or pharmacist first
• other medications – some antihistamines can interact with other medications, so it’s important to check before you start any new medication if they will interact

Best non-drowsy antihistamines

The best non-drowsy antihistamines are second-generation examples, such as:

• loratadine
• fexofenadine
• cetirizine
• desloratadine

The effects of these antihistamines can last for up to 24 hours and are less likely to cause drowsiness compared to first-generation antihistamines. However, it is important to assess how you react to these medications before operating machinery or driving.

Best antihistamines for severe allergic reactions

There is little evidence to suggest that a particular antihistamine is better than another for treating allergy symptoms. However, a severe allergic reaction, also known as anaphylaxis, is a medical emergency and requires immediate attention.

If you or anyone you know is experiencing the following symptoms, call 999 or get someone to take you to A&E:

• swelling of your throat, mouth, tongue, or lips
• difficulty breathing or breathing rapidly
• difficulty swallowing
• wheezing, coughing, or noisy breathing
• tiredness or confusion
• feeling faint, dizzy, or fainting
• skin that feels cold to touch
• blue, grey, or pale skin

Best antihistamines for chronic hives or skin conditions

For chronic hives or skin conditions like urticaria, the first-line treatment usually involves non-sedating antihistamines like:

• cetirizine
• fexofenadine
• loratadin

These are to be taken as needed or regularly for up to 6 weeks. If not effective, you may be given a course of corticosteroids as well.

Best antihistamines for itchy skin

Choosing the best antihistamine for itching will depend on your circumstances. Both sedating and non-sedating antihistamines can provide effective relief from itchy skin.

Sedating antihistamines like diphenhydramine may be preferable if your symptoms are keeping you awake at night, whereas loratadine, cetirizine, or fexofenadine are less likely to cause drowsiness and are better for daytime use.

Best antihistamines for tree pollen

Non-drowsy antihistamines are often recommended for hay fever caused by tree pollen. They offer effective relief without causing drowsiness. At Superdrug Online Doctor, we offer the following oral antihistamines for tree pollen:

• fexofenadine (Telfast)
• cetirizine
• loratadine
• desloratadine (Neoclarityn)

However, you may benefit from a combination of corticosteroids and antihistamines in the form of a nasal spray, such as:

• Dymista
• Ryaltris

Best antihistamines available over the counter

For over-the-counter antihistamines, we recommend:

• fexofenadine 120mg
• cetirizine
• loratadine

These are commonly used for mild to moderate hay fever and other allergic reactions and are available to buy online and in many UK pharmacies.

Although antihistamines are an effective way to relieve hay fever symptoms, they can cause side effects. Most side effects are associated with first-generation antihistamines, particularly drowsiness. The sedating effects of medications like chlorphenamine can make it even more difficult to carry out your daily activities. However, second-generation antihistamines are less likely to make you drowsy or tired.

Some of the common side effects of strong antihistamines include:

• dry mouth
• headache
• dizziness
• feeling sick (nausea)
• blurred vision

Are stronger antihistamines more likely to cause side effects?

Yes, first-generation antihistamines are more likely to cause side effects, especially drowsiness, while second-generation antihistamines like fexofenadine are less likely to cross into the brain, reducing the risk of drowsiness and other cognitive effects.

Antihistamines help relieve hay fever and other allergy symptoms by blocking the effects of histamine. They are available in 2 common types, sedating (first-generation) and non-sedating (second-generation). The best or strongest antihistamine for you will depend on the severity of your symptoms, how quickly you need relief, and whether you need a drowsy or non-drowsy option.

Some of the strongest over-the-counter antihistamines include cetirizine 10mg, fexofenadine 120mg, or loratadine 10mg. However, if you have more severe symptoms, you may need a stronger prescription-only antihistamine like fexofenadine 180mg or desloratadine.

➤ You can request antihistamines and other hay fever treatments from Superdrug Online Doctor following the completion of a short online health questionnaire.

Which antihistamine works the fastest?

Cetirizine is considered a fast-acting antihistamine, getting to work within 30 to 60 minutes. Many people notice an improvement in their symptoms within an hour of taking it.

Can I take 2 antihistamines together for stronger results?

No, it’s not recommended that you take 2 antihistamines together. It is unlikely you will notice stronger results. Instead, you may be at an increased risk of side effects. If you do not think your current antihistamine or dose is working for you, speak to your doctor or pharmacist. They may recommend an alternative hay fever treatment.

Are antihistamine tablets or sprays stronger?

In effect, neither antihistamine tablets nor sprays are stronger, the best choice for you depends on your symptoms. Nasal sprays containing antihistamines are generally more effective and faster acting for treating specific nasal hay fever symptoms. However, many antihistamine nasal sprays also contain a corticosteroid to help reduce inflammation in the nasal passages. Antihistamine tablets may be more effective for other allergy symptoms, like itching.

Is cetirizine the strongest antihistamine?

Cetirizine is one of the stronger second-generation antihistamines available over the counter without a prescription. However, it might not be strong enough for more severe allergies compared to prescription alternatives like desloratadine or fexofenadine 180mg tablets.