Cetirizine vs Loratadine vs Fexofenadine

The Three Non-Drowsy Antihistamines at a Glance

Cetirizine, loratadine and fexofenadine all belong to the same drug class: second-generation (or 'less-sedating') antihistamines. They work by blocking histamine, the chemical your body releases during an allergic reaction that causes sneezing, a runny nose, itchy eyes and hives. Because they were designed to cross into the brain far less than older antihistamines like promethazine, they are much less likely to make you drowsy. In Australia all three are available over the counter without a prescription, both as branded products and as cheaper generics.

How Each One Works in the Body

All three medicines are H1-receptor antagonists, meaning they sit on the same receptors histamine would otherwise activate. The differences come down to how much reaches the brain and how the body clears the drug. Loratadine is broken down (metabolised) in the liver into an active form called desloratadine. Cetirizine and fexofenadine are barely metabolised and are cleared largely by the kidneys, which is why people with reduced kidney function may need a lower dose or a different option.

Fexofenadine is the least sedating because very little of it crosses the blood-brain barrier, the protective filter around the brain. Cetirizine crosses slightly more than the other two, which is why a minority of people notice mild drowsiness on it. Loratadine sits in between. These are general tendencies from clinical studies, not fixed rules, and individual responses vary widely.

Onset and Duration: How Fast and How Long

For sudden symptoms, speed matters. Cetirizine tends to start relieving symptoms fastest, often within an hour, which is one reason pharmacists frequently suggest it for hives or a flare that has already started. Loratadine and fexofenadine usually take a little longer to build effect but reach a similar level of relief. Once they are working, all three last around 24 hours, so a single daily dose is enough for most adults.

Drowsiness: Which Is Genuinely Non-Drowsy?

All three are marketed as non-drowsy, and for most people they are. However, cetirizine has a modestly higher rate of drowsiness in studies than loratadine or fexofenadine, and Australian product information for cetirizine notes that some people may feel sleepy. Fexofenadine has the lowest sedation rate of the three. If you drive, operate machinery or need to concentrate at work, fexofenadine or loratadine may be the safer starting point, though you should see how any new medicine affects you before driving.

What Each One Is Best For

Because the three are similarly effective for hay fever, the deciding factor is often the specific problem you are managing and how your body responds. The list below reflects common patterns rather than fixed rules.

• radio_button_uncheckedCetirizine (Zyrtec): Often favoured for hives (urticaria) and itchy skin, and when you want faster relief. Its slightly higher chance of mild drowsiness can even be a mild advantage for evening dosing.
• radio_button_uncheckedLoratadine (Claratyne): A solid all-rounder for seasonal and year-round hay fever. It is frequently the cheapest of the three as a generic, making it a good value default.
• radio_button_uncheckedFexofenadine (Telfast): Best when staying alert is a priority, such as for shift workers, drivers and students. It is also available in higher strengths (120 mg and 180 mg) for more stubborn symptoms.

Dosing and Children's Options

For adults, the standard doses are cetirizine 10 mg once daily, loratadine 10 mg once daily, and fexofenadine 120 mg or 180 mg once daily. All three come in liquid formulations and lower-strength children's versions, so they can be used across a range of ages, but the minimum age differs by product and strength. Never assume a child's dose from the adult tablet.

Interactions and Things to Watch

The most important practical interaction in this group belongs to fexofenadine. Fruit juices — particularly apple, orange and grapefruit — can significantly reduce how much fexofenadine your body absorbs, and so can antacids containing aluminium or magnesium. Take fexofenadine with water, and separate it from antacids by a couple of hours, to get the full effect.

Cetirizine and fexofenadine are cleared mainly by the kidneys, so people with significant kidney impairment may need a reduced dose. Loratadine is processed by the liver, which is worth mentioning to your pharmacist if you have liver problems or take several other medicines. As a general rule, tell your pharmacist about everything else you take so they can check for interactions specific to your situation.

Generics and Cost in Australia

All three actives are available as pharmacy and supermarket generics that contain exactly the same active ingredient as the branded product. A home-brand box of cetirizine or loratadine is often a fraction of the price of Zyrtec or Claratyne, yet delivers the identical medicine at the identical dose. Loratadine generics are frequently the cheapest per tablet, while fexofenadine tends to sit at the higher end, especially in the 180 mg strength.

Prices vary between pharmacies and change over time, so it is worth comparing the price per tablet rather than the price per box, as pack sizes differ. Buying a larger pack usually lowers the cost per dose if you use an antihistamine regularly through a season.

The products below are the branded originals for each active ingredient. Equivalent generics are widely available and typically cheaper. Check your preferred pharmacy for current pricing.

How to Choose Between Them

There is no single winner, because the differences are small and personal. A sensible approach is to start with the medicine that matches your main priority — speed and hives point towards cetirizine, value towards loratadine, and staying alert towards fexofenadine — then give it a fair trial of several days of daily use. If it does not control your symptoms, switching to another antihistamine in this group is a reasonable next step, since people who respond poorly to one sometimes do well on another.

FAQ

Why is loratadine sometimes preferred over cetirizine?

Loratadine is often preferred because it has a slightly lower chance of causing drowsiness than cetirizine while still relieving hay fever effectively, and as a generic it is frequently the cheapest of the group. That said, cetirizine tends to act faster and is often the better pick for hives. Neither is universally 'better' — the right choice depends on whether you prioritise minimal drowsiness and cost, or faster onset.

What is the best antihistamine in Australia?

There is no single best antihistamine for everyone. Cetirizine, loratadine and fexofenadine are all effective, once-daily, less-sedating options available over the counter, and studies show they relieve hay fever to a broadly similar degree. The best one for you depends on how quickly you need relief, how sensitive you are to drowsiness, what you are treating, and cost. A pharmacist can help you match one to your symptoms.

Which is better, cetirizine or loratadine 10 mg?

Both are taken as a 10 mg once-daily dose and both work well for hay fever. Cetirizine 10 mg usually starts working faster and may be more effective for itchy skin and hives, but it is a little more likely to cause mild drowsiness. Loratadine 10 mg is slightly less sedating and often cheaper. If one does not suit you, it is reasonable to try the other.

Which is better, loratadine or Zyrtec?

Zyrtec is the brand name for cetirizine, so this is really cetirizine versus loratadine. Cetirizine (Zyrtec) generally acts faster and is often favoured for hives, while loratadine is marginally less sedating and usually cheaper as a generic. Both provide around 24 hours of relief from a single daily dose. Many people simply choose based on which one has worked best for them in the past.

Can I switch from cetirizine to loratadine (or to fexofenadine)?

Yes. If one antihistamine in this group is not controlling your symptoms or is causing side effects, switching to another is a common and reasonable step, and people who respond poorly to one sometimes do better on another. You generally do not need a washout period between them, but it is worth checking with your pharmacist, especially if you take other medicines or have kidney or liver problems.

Why should fexofenadine not be taken with fruit juice?

Fruit juices such as apple, orange and grapefruit can reduce how much fexofenadine your body absorbs, making it less effective. For this reason fexofenadine is best taken with water. Antacids containing aluminium or magnesium can also lower its absorption, so separate them by a couple of hours. Cetirizine and loratadine do not have this particular limitation.