Experts rate the very rare, but potentially serious, side effects of over-the-counter nasal decongestants.
They review antibiotics that contain pseudoephedrine because it may cause the vessels supplying the brain to constrict or spasm, reducing blood flow.
What is worrying is that this might lead to seizures and even a stroke.
But the competent authorities confirm that the possibility of this happening is very low.
The packages of these products already contain warnings regarding rare risks that patients can read following they buy the medicine. Other, more common side effects are headache and dizziness.
Experts say anyone with concerns regarding these drugs should speak to a doctor or pharmacist. All medicines can have some side effects.
People take pseudoephedrine to relieve nasal congestion. It’s sold as a spray, liquid, and tablet, and is sometimes mixed with other cough, cold, or allergy medications.
Medication can help clear blocked airways and reduce obstruction by affecting the blood vessels in the nose.
The UK-wide review of pseudoephedrine began following drug regulators in France alerted their European counterparts, who had begun a review, regarding some recent and rare cases.
The experts will look at two vascular conditions of the brain – one is reversible posterior encephalopathy syndrome and the other is reversible cerebral vasoconstriction syndrome.
This can cause a sudden, severe, thunderclap-like headache, which may recur over days and sometimes weeks.
Symptoms include blurred vision, headache, seizures, and confusion.
In the UK, people can report any suspected side effects from medicines to the competent authorities who run the Medicines and Healthcare Products Regulatory Agency.
The agency says it has received a very small number of recent reports of reversible posterior encephalopathy syndrome — one case from which the person has recovered, another case of reversible cerebral vasoconstriction syndrome and has determined the outcome to be unknown.
A spokesperson said: “We keep the safety of all medicines under close review to ensure the benefits outweigh any risks – the safety of the public is our highest priority.”
“We are reviewing the available evidence and will provide any further advice as needed.”
“If you have any concerns regarding your medication, please seek advice from a healthcare professional.”
The Royal Pharmaceutical Society said pseudoephedrine was widely used and that these medicines were carefully evaluated before they were made available to the public.
Claire Anderson, chair of the association, said: “When new risks emerge, it can be concerning for patients. It is right that the relevant authorities investigate and we await the results of the reviews.”