Clarex is desloratadine 5 mg, a once-daily antihistamine for allergies. It treats hay fever, year-round allergic rhinitis, hives and allergic itching. It comes as a tablet, a tablet that melts on the tongue, and an oral solution for children.
What is Clarex?
The South African Medicine Price Registry lists three presentations, all Schedule 2 — available from a pharmacy without a prescription:
| Product | Form | Strength |
|---|---|---|
| Clarex | Tablet | Desloratadine 5 mg |
| Clarex ODT 5 | Orally disintegrating tablet | Desloratadine 5 mg |
| Clarex Oral Solution | Solution | Desloratadine 2.5 mg / 5 ml |
Desloratadine is a second-generation antihistamine, and its relationship to loratadine explains the dose. When you take loratadine, the liver converts it into desloratadine, which does the actual work. Desloratadine skips that step — which is why 5 mg here matches loratadine 10 mg, and why it depends less on liver function.
It blocks H1 histamine receptors. Histamine, released by mast cells during an allergic reaction, causes the swelling, itching, sneezing and mucus that follow; blocking its receptors interrupts the process.
Because it barely crosses into the brain, desloratadine is among the least sedating antihistamines — less so than cetirizine, and comparable to loratadine. It usually works within an hour and lasts a full day.
The ODT dissolves on the tongue without water, which suits children, people who struggle with tablets, and anyone taking it away from a glass of water. The solution is for children, dosed by age and weight.
Desloratadine is sold in South Africa under several names, including Dazit. Being given one instead of another is ordinary substitution.
What is Clarex commonly used for?
- Hay fever and seasonal allergic rhinitis — sneezing, runny nose, nasal itching, itchy and watery eyes.
- Year-round allergic rhinitis, from dust mites, pets, mould or cockroach allergen.
- Chronic urticaria (hives) and allergic itching.
- Itchy skin in allergic rashes and some eczema flares.
- Insect bite reactions.
- Allergic conjunctivitis.
- Mild allergic reactions, alongside — never instead of — proper emergency treatment for anything severe.
Three practical limits are worth knowing.
It does not treat colds or flu. Those are viral. Fever and body aches point away from allergy entirely, and an antihistamine will do very little.
It does little for a blocked nose. Antihistamines handle sneezing, itching and running well and congestion poorly. Persistent blockage responds better to a steroid nasal spray, which acts on the inflammation directly.
Take it regularly through a season. For predictable seasonal allergy, daily use from the start of the season works considerably better than waiting for symptoms to build and then reacting to them.
How Clarex fits into this medicine category
| Group | Examples | Notes |
|---|---|---|
| Second-generation antihistamines | Desloratadine (Clarex), loratadine, cetirizine (Austell Cetirizine), fexofenadine | Once daily; least sedating |
| First-generation antihistamines | Chlorphenamine (Rhineton), promethazine | Effective but markedly sedating |
| Steroid nasal sprays | Fluticasone, mometasone | Best for persistent nasal allergy, especially congestion |
| Decongestants | Pseudoephedrine, oxymetazoline | Blockage only; short-term; blood pressure cautions |
| Leukotriene blockers | Montelukast | Allergic rhinitis with asthma |
| Eye drops | Antihistamine or cromoglycate drops | Eye symptoms specifically |
For moderate or persistent allergic rhinitis, an antihistamine plus a steroid nasal spray generally works better than either alone. See the allergy, cold and flu medicines hub.
What to check before using Clarex
Speak to a pharmacist or doctor if you:
- Have kidney disease or reduced kidney function — the dose may need adjusting.
- Have liver disease.
- Have epilepsy or a history of seizures.
- Are pregnant or breastfeeding.
- Are already taking another antihistamine, including one hidden inside a cold and flu remedy. Doubling up adds side effects without adding benefit, and it happens easily.
- Are buying for a child. Use the solution at the dose for their age and weight; adult tablets are not suitable for young children.
- Have phenylketonuria or need to check the excipients in the ODT or solution.
Practical points:
- Take it once daily at the same time, with or without food.
- ODT tablets go on a dry tongue and dissolve — handle them with dry hands and do not push them through the foil roughly.
- Measure the solution with the device supplied, not a kitchen spoon.
- Although drowsiness is uncommon, find out how it affects you before driving.
- If you are due for allergy skin prick testing, antihistamines interfere with the results and usually need stopping several days beforehand. Ask before booking.
Possible cautions and when to ask a pharmacist or doctor
Desloratadine is very well tolerated. The commonest effects are headache, tiredness, dry mouth and occasionally nausea. In children, restlessness or irritability is sometimes seen instead of sedation.
Get emergency help immediately for signs of a severe allergic reaction — swelling of the lips, tongue or throat, difficulty breathing or swallowing, widespread hives with faintness, or collapse. Anaphylaxis is treated with adrenaline. An antihistamine tablet is not adequate treatment for it, and taking one instead of calling for help wastes time that matters.
Contact a doctor if:
- Symptoms are not controlled after a week or two of regular use.
- You need an antihistamine most days for months — a steroid nasal spray, allergy testing or immunotherapy may serve you better.
- Hives last more than six weeks, or come with joint pain, fever or weight loss.
- You have wheezing, chest tightness or breathlessness. Allergy and asthma frequently travel together, and asthma needs its own treatment.
- A child becomes unusually agitated, drowsy or unwell on it.
- You have kidney problems and have not had the dose checked.
Related medicine guides
- Browse Allergy, Cold & Flu Medicines guides
- Read: Austell Cetirizine used for
- Read: Rhineton used for
Frequently asked questions
What are Clarex tablets used for? Allergies — hay fever, year-round allergic rhinitis, hives, allergic itching and allergic eye symptoms. It contains desloratadine 5 mg.
What is Clarex 5 used for? The same conditions. The 5 refers to 5 mg of desloratadine per tablet.
Is it the same as loratadine? Desloratadine is what your body converts loratadine into. Clarex delivers it directly, so 5 mg matches loratadine 10 mg.
Will it make me drowsy? Rarely. It is among the least sedating antihistamines, though a small number of people still feel tired on it.
How quickly does it work? Usually within an hour, lasting about a day, so it is taken once daily.
What is Clarex ODT? An orally disintegrating tablet that dissolves on the tongue without water.
Will it unblock my nose? Not much. For congestion, a steroid nasal spray usually works better.
Do I need a prescription? No. It is Schedule 2 — available from a pharmacy without one.