Blexten (Bilastine): Uses, Dosage, Side Effects and Cost in Canada

Blexten (bilastine) is a prescription antihistamine for hay fever and chronic hives. Learn how to take it on an empty stomach, its side effects and heart rhythm warnings.

allergyDoctor-reviewedPrescriptionAvailable in Canada
Illustration of a blister strip of tablets for Blexten (bilastine)

Disclaimer: This article is for informational purposes only and does not constitute medical advice. It is not intended to be a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of a physician or other qualified health provider with any questions you may have regarding a medical condition.

Overview

Bilastine is a prescription antihistamine used to relieve the symptoms of hay fever (seasonal allergic rhinitis) and chronic spontaneous urticaria, also called chronic hives. In Canada the original brand is Blexten, and generic bilastine 20 mg tablets are also sold. Blexten is also made as eye drops, which are a separate product and are not covered on this page.

It eases sneezing, a runny or blocked nose, itchy or watery eyes, and the itching and welts of hives. It does not cure allergies and works only while it is taken. It is taken on an empty stomach, and it has a warning about heart rhythm (the QT interval), so a prescriber checks your health history and other medicines first.

If allergy symptoms are not controlled by over-the-counter antihistamines, BC residents can speak with a BC-licensed doctor by phone through Avee Health about their symptoms and next steps. A prescription is not guaranteed.

In Canada, Blexten tablets are authorized for:

  • Relief of nasal and non-nasal symptoms of seasonal allergic rhinitis (hay fever), such as sneezing, a runny or blocked nose and itchy, watery eyes
  • Relief of the symptoms of chronic spontaneous urticaria (long-lasting hives), such as itching and hives

Health Canada has authorized it for patients 4 years of age and older who weigh at least 16 kg. It is not authorized for children under 4.

Generic name

Bilastine

Drug class

Second-generation antihistamine (H1-receptor antagonist)

Category

allergy

Availability

Prescription required

In Canada

Available

How Blexten Works

Bilastine is an antihistamine. It blocks histamine H1 receptors in the body, so histamine from an allergic reaction cannot cause sneezing, itching, a runny nose, watery eyes or hives. It reaches only limited amounts in the brain, which is why it is much less sedating than older antihistamines such as diphenhydramine.

The body does not break bilastine down. About 95% of a dose leaves unchanged in the stool and urine, so it does not interact with liver enzymes. Its half-life is about 14.5 hours.

Dosage Instructions of Blexten

Take bilastine exactly as your prescriber directs. The Canadian Blexten product monograph gives this usual dose for adults and adolescents:

  • One 20 mg tablet once a day, for hay fever (seasonal allergic rhinitis) or chronic hives
  • The maximum is one 20 mg tablet a day. Do not take more.
  • Swallow the tablet with water on an empty stomach: wait one hour after taking it before eating or drinking fruit juice, or take it at least two hours after food or juice. Food, grapefruit juice and other fruit juices lower how much medicine your body absorbs.
  • No dose change is needed for older adults or for kidney or liver problems. Children aged 4 to 11 who weigh at least 16 kg have a dose set by the prescriber from the current product monograph.

Missed dose: take the next scheduled dose. Do not take an extra dose.

Storage Instructions

Store at room temperature, between 15°C and 30°C. Keep out of the reach and sight of children. Do not use after the expiry date on the carton or blister.

Side Effects of Blexten

In placebo-controlled trials of 20 mg a day, the most common side effects were, compared with placebo:

  • Headache: 4.3%, compared with 3.0%
  • Drowsiness (somnolence): 4.1%, compared with 2.6%
  • Dizziness: 1.1%, compared with 0.4%
  • Upper stomach pain: 1.1%, compared with 0.4%

Less often, people had dry mouth, nausea, tiredness or changes in heart rhythm on a heart tracing. Blood test results (such as liver tests) can change, and your doctor decides when to check them.

Get medical help right away if you have:

  • A racing, pounding, slow or irregular heartbeat, cold sweats, feeling faint or fainting, which can be heart rhythm problems
  • Trouble breathing, or swelling of the face, lips, tongue or throat, or swelling and redness of the skin, which can be an allergic reaction

Important Safety Information About Blexten

  • Heart rhythm: bilastine can lengthen the QT interval and may raise the risk of a dangerous heart rhythm (torsade de pointes). Do not take it if you have ever had QT prolongation or torsade de pointes, including congenital long QT syndrome.
  • Extra caution: tell your prescriber if you have an irregular heartbeat, a very slow heartbeat, low potassium or magnesium, a family history of sudden cardiac death, or take other QT-lengthening medicines.
  • Allergy: do not take it if you are allergic to bilastine or any ingredient. Serious allergic reactions have been reported.
  • Kidneys: with moderate or severe kidney problems, taking it with P-glycoprotein inhibitors such as ketoconazole, erythromycin, cyclosporine, ritonavir or diltiazem should be avoided, because levels can rise and side effects become more likely.
  • Liver: it has not been studied in liver disease, but no dose change is expected to be needed because the body does not break it down.
  • Pregnancy and breastfeeding: avoid it during pregnancy unless a doctor advises otherwise. Talk to your prescriber before breastfeeding.
  • Driving: a few people feel tired. If you do, do not drive or use machinery.

Drug Interactions

Tell your prescriber and pharmacist about everything you take, including vitamins and natural products. Points to know:

  • Ketoconazole and erythromycin roughly doubled bilastine levels and increased its effect on the QT interval. Other P-glycoprotein inhibitors, such as ritonavir, cyclosporine and diltiazem, can also raise levels. The monograph advises against combining them
  • Other medicines that lengthen the QT interval, or that cause low potassium or magnesium: using them with bilastine is not recommended
  • Grapefruit juice and other fruit juices lower absorption. Rifampicin and ritonavir may also lower bilastine levels
  • Lorazepam and alcohol: bilastine did not add to their effects in studies
  • Interactions with herbal products have not been studied

Brands & DIN Number of Blexten

Brand Names

Blexten

Key Takeaways

  • 1Blexten (bilastine) is a prescription antihistamine authorized in Canada for hay fever (seasonal allergic rhinitis) and chronic spontaneous hives.
  • 2The usual dose is one 20 mg tablet once a day, taken with water on an empty stomach.
  • 3Food and fruit juice lower how much is absorbed. Wait one hour before eating or drinking juice, or take it two hours after.
  • 4The most common side effects are headache, drowsiness, dizziness and upper stomach pain.
  • 5It can lengthen the QT interval. It must not be used by people with a history of QT prolongation or torsade de pointes, including congenital long QT syndrome.
  • 6Avoid it with certain antifungals and antibiotics (such as ketoconazole and erythromycin) and with other QT-lengthening medicines.
  • 7Get urgent help for a racing, slow or irregular heartbeat, fainting, or swelling of the face, lips or throat.

Frequently Asked Questions

Do I need a prescription for Blexten in Canada, and how do I get it in BC?
Yes. Blexten is a prescription medicine in Canada. BC residents can speak with a BC-licensed doctor by phone through Avee Health about their symptoms and whether bilastine is appropriate. The doctor will ask about heart rhythm problems and your other medicines, because bilastine can affect the QT interval. A prescription is not guaranteed.
How fast does Blexten work?
In an allergen chamber study, the effect began about 1 hour after the tablet and lasted about 26 hours, which is why it is taken once a day.
Why must Blexten be taken on an empty stomach?
Food and fruit juice lower how much bilastine your body absorbs. A high-fat breakfast reduced the peak level by about a third, and grapefruit juice reduced absorption by about 30%. Take it with water, one hour before food or two hours after.
Does Blexten make you drowsy?
Drowsiness was uncommon. In trials of 20 mg a day, somnolence was reported by 4.1% of people taking bilastine and 2.6% taking placebo. Bilastine did not impair driving in a driving test, but a few people feel tired, so see how you react before driving.
How is Blexten different from Reactine and Claritin?
All three are second-generation antihistamines. Reactine (cetirizine) and Claritin (loratadine) are sold without a prescription, while Blexten needs one. Blexten must be taken on an empty stomach and has a heart rhythm warning that the others do not carry in the same way. A doctor can help you choose.
Can I take Blexten while pregnant or breastfeeding?
The monograph advises avoiding Blexten during pregnancy unless a doctor says otherwise. Animal studies show it passes into milk, and its effect in human milk is not known, so ask your prescriber before breastfeeding.
Can I drink alcohol while taking Blexten?
In a study, alcohol together with bilastine affected thinking and coordination no more than alcohol together with placebo. Alcohol can still make you drowsy, so drink carefully and avoid driving if you feel tired.
How much does Blexten cost in Canada?
The price depends on the number of tablets and the pharmacy, and generic bilastine tablets are also sold in Canada. Coverage varies by plan, so check with your pharmacy or insurer.
Written By
Avee Editorial

Avee Editorial

Avee Editorial Team