Answer the side-effect intent for allergex without diagnosing; distinguish common from serious reactions and give safe next-step/reporting guidance.
Source
Clinical statements on this page are taken from the SAHPRA-approved patient information leaflet (approved 08/03/2024) and professional information (approved 08/03/2024) for this product: patient information leaflet, professional information. Retrieved 2026-09-03. Where this page and the approved leaflet differ, the leaflet is correct.
What is Allergex?
Allergex contains the active ingredient Chlorpheniramine maleate.
- Active ingredient — Chlorpheniramine maleate
- Registration holder — Adcock Ingram Limited
It is approved for:
- ALLERGEX TABLETS is used for the treatment of allergic and anaphylactic conditions such as hay fever, vasomotor rhinitis (allergy in the nose when the small blood vessels in the nose dilate causing nasal congestion), urticaria (itchy rash that appears on the skin), angioedema (swelling under the skin), drug reactions, contact dermatitis, atopic dermatitis, insect bites, pruritus and pruritus vulvae
Common side effects of Allergex
Not everyone gets side effects. The effects below are those listed in the South African approved leaflet, grouped using the leaflet’s own frequency wording.
About these frequency terms
This leaflet groups effects as “Frequent” and “Less frequent” rather than the very common/common/uncommon scale used in some other markets.
Frequent side effects
- sedation (calming or relaxing state)
- incoordination
- dizziness
- Blurred vision
- Headache
- Nausea (feeling that one is about to vomit)
Frequency unknown side effects
- vomiting (to be sick)
- diarrhoea (frequent or loose watery stools)
- constipation
- Increased appetite
- Stomach pain
- dry mouth
- allergic reactions and cross sensitivity to related medicines
- anorexia (loss of appetite)
- muscle weakness
- painful urination
- tachycardia (increased heart rate)
- tremors (shaking)
- convulsions (an episode of spasm(s) and reduced consciousness)
- tightness of the chest
- hypotension (low blood pressure)
- tinnitus (ringing in the ears)
Serious side effects and warning signs
This leaflet does not set out a separate list of serious side effects. The general warning signs below apply to any medicine.
General warning signs that apply to any medicine
Call for emergency help now if any of these happen
- Difficulty breathing, wheezing, or tightness in the throat or chest
- Swelling of the face, lips, tongue or throat
- A widespread rash with blistering or peeling skin, or sores in the mouth, eyes or genitals
- Fainting, collapse, or a sudden severe drop in alertness
- Chest pain, or sudden weakness or numbness on one side of the body
- A fit (seizure), or confusion that comes on suddenly
In South Africa call 10177 for an ambulance, or 112 from a mobile phone. Go to your nearest emergency department if it is faster. Do not wait to see whether the symptom settles.
How long can side effects last?
How long a side effect lasts depends on the effect, the product, how long it has been used, and the person. Some effects ease within days as the body adjusts. Others continue for as long as the product is used. A few can persist after stopping, and some need review rather than waiting.
- Settling effects — mild effects that ease over the first days or weeks of use
- Ongoing effects — effects that continue while the product is being used and improve after stopping
- Persistent effects — effects that continue after stopping and need medical review
- Delayed effects — effects that appear after weeks or months rather than immediately
Which of these applies to a particular effect is a clinical question. If a side effect is not settling, is getting worse, or is affecting your daily life, that is worth a conversation with a pharmacist or doctor regardless of how long it has been going on.
Evidence required before publish — source the following for Allergex from the SAHPRA-approved patient information leaflet or professional information, and cite what you actually used.
- Anything the approved information for Allergex says about how long specific effects last
- Whether the source describes any effect as usually temporary, or as needing review if it persists
- Whether any effect is described as continuing after the product is stopped
Factors that may affect side effects
The approved leaflet identifies the following cautions and factors.
Do not use it at all if
- If you are hypersensitive (allergic) to chlorphenamine maleate or any of the other ingredients of ALLERGEX TABLETS (listed in section 6)
- If you suffer from recurrent seizures (Epilepsy)
- If you suffer from acute attacks of asthma
- ALLERGEX TABLETS should not be administered to Premature infants and new-born babies
Use with care, and tell your doctor, if
- The use of this medicine leads to drowsiness which is worsened by the simultaneous intake of alcohol. Patients should be warned not to drive a motor vehicle or operate machinery as impaired decision making could lead to accidents
- If you consume other central nervous system depressants eg sedatives and tranquilizers (sleeping tablets which result in a calming effect). This may lead to drowsiness and impaired concentration
- If you suffer from prostatic hypertrophy (enlarged prostate)
- If you suffer from increased pressure in the eye (glaucoma)
- If you suffer from urinary retention (unable to empty your bladder)
- ALLERGEX TABLETS may suppress positive skin test results and should be stopped several days before the test
Pregnancy and breastfeeding
- If you are pregnant or breastfeeding your baby, think you may be pregnant or planning to have a baby, please consult your doctor, pharmacist or other healthcare professional for advice before taking this medicine
- Safety of ALLERGEX TABLETS in pregnancy and breastfeeding has not been established
- Driving and using machinery ALLERGEX TABLETS may make you sleepy and reduce your level of concentration or alertness
- Do not drive or operate any tools or machines as this medicine may interfere with your ability to do these safely
- Taking this medicine with alcohol and other medicines to treat depression may worsen these effects
- It is not always possible to predict to what extent ALLERGEX TABLETS may interfere with the daily activities of a patient
Interactions and medicines to check
The approved leaflet names these interactions.
- Medicines that cause depression of the central nervous system (such as those used for insomnia or anxiety)
- Medicines to treat epilepsy (phenytoin)
- Medicines used to treat depression, Parkinson’s disease, or other diseases
- Medicines that stop the action of the enzyme monoamine oxidase (antidepressants)
Bring the actual products to the conversation
A pharmacist can check for interactions much faster from the packaging than from remembered names.
What to do if you experience side effects
If you think you are having a side effect, the response depends on how severe it is. Use the warning signs above first — if any of those apply, treat it as urgent.
If the symptom is severe or frightening
Get medical help immediately. Call 10177 for an ambulance, or 112 from a mobile phone, or go to the nearest emergency department. Take the product and its packaging with you if you can.
If the symptom is mild but bothering you
- Write down what the symptom is, when it started, and how it relates to when you take the product
- Check the leaflet that came with the product to see whether the symptom is listed
- Speak to your pharmacist — for many questions this is the fastest route to a useful answer
- Contact the prescriber if the symptom is affecting your daily life or is not settling
Do not stop a prescribed treatment on your own
Stopping some treatments suddenly causes its own problems, and the condition being treated may get worse. If you want to stop, ask a pharmacist or doctor how to do it safely — they can usually offer an alternative.
You can also report a suspected side effect in South Africa. Reporting does not replace getting medical advice, and you do not need to be certain the product was the cause.
When to seek urgent medical help
Some symptoms need medical attention straight away rather than an appointment in a few days. Do not wait to see whether they settle.
Call for emergency help now if any of these happen
- Difficulty breathing, wheezing, or tightness in the throat or chest
- Swelling of the face, lips, tongue or throat
- A widespread rash with blistering or peeling skin, or sores in the mouth, eyes or genitals
- Fainting, collapse, or a sudden severe drop in alertness
- Chest pain, or sudden weakness or numbness on one side of the body
- A fit (seizure), or confusion that comes on suddenly
In South Africa call 10177 for an ambulance, or 112 from a mobile phone. Go to your nearest emergency department if it is faster. Do not wait to see whether the symptom settles.
Get same-day medical advice if you have
- A high fever, or a rash together with feeling generally unwell
- Yellowing of the eyes or skin, or unusually dark urine
- Unusual bruising or bleeding that you cannot explain
- Severe or persistent vomiting or diarrhoea, especially if you cannot keep fluids down
- A sudden change in mood, or thoughts of harming yourself
- Any symptom that is rapidly getting worse
If you are having thoughts of harming yourself
Help is available in South Africa. The SADAG helpline is 0800 567 567, or you can go to your nearest emergency department. You do not have to wait until it feels like an emergency.
How to report a suspected side effect in South Africa
South Africa has an official system for reporting suspected side effects, run by the South African Health Products Regulatory Authority (SAHPRA). Reports from the public and from healthcare professionals are how safety signals get detected after a product is already in use.
Who can report
Anyone can report — you do not have to be a healthcare professional, and you do not need to prove that the product caused the problem. A suspicion is enough. Patients, caregivers and family members can all submit a report.
What to have ready
- The name of the product, its strength and form, and the batch number if you have it
- Why it was being used, and when it was started and stopped
- What the suspected reaction was, when it began, and how long it lasted
- Any other medicines, supplements or remedies being used at the same time
- Basic details about the person affected — age and sex are usually enough
How to report
SAHPRA accepts adverse reaction reports through its e-Services reporting system and through the Med Safety mobile app. Healthcare professionals can also report through the same routes. Current forms and access points are published on the SAHPRA site.
- SAHPRA Health Products Vigilance — the main vigilance and reporting hub
- SAHPRA e-Services — current adverse reaction reporting access
Reporting is not a substitute for medical care
If someone is unwell now, get medical help first and report afterwards. Urgent symptoms always take precedence over paperwork.
For a fuller walkthrough see how to report an adverse drug reaction.
Related pages
← Back to more medicine side effects.
Report a side effect
If you think you have had a side effect, you can report a suspected side effect in South Africa. Report a suspected side effect through the appropriate SAHPRA pathway where relevant.
Information only
This page gives general medicine-safety information for people in South Africa. It is not a diagnosis and not personalised medical advice. It cannot tell you whether a symptom you are having is caused by a particular product. Speak to a pharmacist or doctor about your own situation, and do not stop or change a prescribed treatment on the basis of a web page.
Editorial status: draft — not for publication
Brief SE-00179 · build rank 179 · Phase 1 · Tier 1. Every evidence slot on this page must be completed from the SAHPRA-approved source and the page signed off by a qualified clinical or pharmacy reviewer before it is published. Target length 1,500–2,200 words.