Telfast contains fexofenadine, a non-sedating antihistamine. It is used for hay fever and allergic rhinitis, and for chronic hives. It comes as 120 mg and 180 mg tablets and as a 30 mg/5 ml suspension for children. It is the least sedating of the commonly used antihistamines.
What is Telfast?
Telfast is Schedule 1 in South Africa, available from a pharmacy:
| Product | Contains | Typical use |
|---|---|---|
| Telfast 120 mg | Fexofenadine 120 mg tablet | Allergic rhinitis, hay fever |
| Telfast 180 mg | Fexofenadine 180 mg tablet | Chronic hives |
| Telfast suspension | Fexofenadine 30 mg/5 ml | Children |
The same ingredient is sold under several other names in South Africa — see the Fexo guide. Being dispensed one rather than another is ordinary generic substitution.
Fexofenadine is a third-generation antihistamine. It blocks histamine H1 receptors, reducing the sneezing, itching, runny nose and watery eyes that histamine produces during an allergic reaction.
Its defining feature is how little enters the brain. Fexofenadine is the active breakdown product of an older antihistamine, terfenadine, and it is actively pumped out of the brain by a transporter called P-glycoprotein. The result is that fexofenadine is the least sedating of the commonly used antihistamines — less so than cetirizine, which causes drowsiness in a meaningful minority, and less than loratadine.
That is why it is the usual choice where alertness genuinely matters — for drivers, pilots, machine operators and students.
Its predecessor is worth a word, because it explains why fexofenadine exists. Terfenadine was withdrawn after it was found to cause dangerous heart rhythm disturbances when its breakdown was blocked by certain other medicines. Fexofenadine is the active product itself, so it does not require that conversion and does not carry the same risk. It is a case of a safety problem being solved properly rather than managed with warnings.
The strength difference reflects the condition, not severity. 120 mg is standard for allergic rhinitis; 180 mg is used for chronic hives, which typically needs more.
What is Telfast commonly used for?
- Seasonal allergic rhinitis (hay fever) — sneezing, runny nose, itchy nose and throat, watery itchy eyes.
- Perennial allergic rhinitis, from dust mites, pets or mould.
- Chronic idiopathic urticaria — persistent hives without an identified cause, usually at 180 mg.
- Itchy allergic skin reactions.
- Allergic conjunctivitis.
- Allergy symptoms in children, using the suspension.
- Allergy where drowsiness must be avoided.
Antihistamines work better taken before or early in an exposure than once symptoms are established. For seasonal allergy, starting before the season and taking it regularly works better than reaching for it after a bad day.
What it does not do: it will not clear a blocked nose well, since congestion comes largely from leukotrienes rather than histamine; it does not treat colds or flu, which are viral; and it does not treat asthma.
For persistent allergic rhinitis, a steroid nasal spray is the most effective treatment — better than any antihistamine tablet, and particularly better for congestion. Tablets are often used alongside a spray.
How Telfast fits into this medicine category
| Group | Examples | Notes |
|---|---|---|
| Non-sedating antihistamines | Fexofenadine (Telfast), loratadine, cetirizine | Allergy without significant sedation |
| Sedating antihistamines | Chlorphenamine, promethazine | Allergy and itch; marked drowsiness |
| Steroid nasal sprays | Fluticasone, budesonide | Most effective for persistent allergic rhinitis |
| Leukotriene antagonists | Montelukast | Congestion, and allergy with asthma |
| Decongestants | Pseudoephedrine (Decofed) | Blocked nose; short-term only |
| Mast cell stabilisers | Sodium cromoglicate | Preventive, eye and nasal |
Among the non-sedating options, fexofenadine sedates least, cetirizine tends to work fastest, and individuals genuinely respond differently. See the allergy, cold, flu and respiratory medicines hub.
What to check before using Telfast
Do not take it with fruit juice. This is the practical point most specific to fexofenadine: apple, orange and grapefruit juice reduce its absorption substantially — by around a third or more — by blocking the transporter that carries it into the bloodstream. Take it with water, and leave a few hours between the tablet and fruit juice. This is a genuine and frequently overlooked reason it seems not to work.
Separate it from antacids containing aluminium or magnesium by at least two hours.
Do not take more than one antihistamine at a time without advice, including combination cold and flu products.
Speak to a pharmacist or doctor first if you:
- Have kidney disease, which may mean a lower dose.
- Have heart disease or a rhythm disorder.
- Are elderly.
- Are pregnant or breastfeeding.
- Are giving it to a child. The suspension is dosed by age and weight — ask a pharmacist rather than splitting adult tablets, which cannot be divided accurately.
- Are due to have allergy skin testing. Antihistamines suppress the reaction and must usually be stopped several days beforehand — mention it in advance, or the test may need repeating.
Shake the suspension well before each dose and use the measuring device supplied.
Possible cautions and when to ask a pharmacist or doctor
Fexofenadine is very well tolerated. Common effects are headache, drowsiness (uncommon), dizziness and nausea.
Seek medical attention urgently if you develop:
- Swelling of the face, lips, tongue or throat, or difficulty breathing or swallowing — signs of a serious allergic reaction. Call emergency services.
- A widespread rash with feeling unwell, or blistering or peeling skin.
- A fast or irregular heartbeat, or fainting.
- Yellowing of the eyes or skin.
See a doctor rather than continuing self-treatment if:
- Symptoms persist despite regular treatment, or you need it every day for months.
- Hives are persistent, recurrent, or last more than six weeks. Chronic urticaria needs assessment, and higher doses under supervision are often effective.
- Hives come with swelling of the lips, tongue or throat, or breathing difficulty — this is an emergency.
- You have wheezing, chest tightness or breathlessness, as asthma commonly accompanies allergic rhinitis.
- Symptoms follow a food, medicine or insect sting. An antihistamine tablet is not adequate treatment for anaphylaxis.
- You have facial pain, thick discoloured discharge or fever, suggesting sinus infection.
- One-sided nasal blockage or nosebleeds, which need examination.
- A child’s symptoms are not settling, or they have breathing difficulty.
If you have been prescribed an adrenaline auto-injector, carry it. An antihistamine does not replace it.
Related medicine guides
- Browse Allergy, Cold, Flu & Respiratory Medicines guides
- Read: Austell Cetirizine used for
- Read: Rhineton used for
Frequently asked questions
What are Telfast tablets used for? Hay fever and allergic rhinitis — sneezing, runny nose, itchy watery eyes — and chronic hives. Telfast contains fexofenadine.
What is Telfast suspension used for? The liquid form for children, dosed by age and weight, for the same allergic symptoms. Ask a pharmacist for the correct amount.
What is Telfast 180 mg used for? Chronic hives (urticaria), which typically needs the higher strength. 120 mg is standard for allergic rhinitis.
Does it make you drowsy? Rarely. Fexofenadine is the least sedating of the common antihistamines, which is why it suits drivers and anyone needing full alertness.
Why should I avoid fruit juice with it? Apple, orange and grapefruit juice reduce absorption substantially by blocking the transporter that carries it into the blood. Take it with water.
Can I give it to my child? Yes, using the suspension at the right dose for age and weight. Do not split adult tablets — ask a pharmacist.
Will it clear a blocked nose? Not well. Congestion comes largely from leukotrienes rather than histamine. A steroid nasal spray is more effective.
Can I take it every day? Many people do through an allergy season. Needing it continuously for months is worth discussing with a doctor.