Britons taking a popular nerve pain drug have been warned that bottles of the medication may contain crystallised 'particles'.

Health chiefs have issued a defect notification for multiple batches of the oral liquid version of gabapentin, manufactured by pharmaceutical company Relonchem.

Gabapentin is prescribed to millions of adults in the UK each year to treat nerve pain and epilepsy, as well as complications from diabetes and shingles. 

But the Medicines and Healthcare products Regulatory Agency (MHRA) has put patients and doctors on alert after saying 'crystals' had been found in bottles of Relonchem's 50mg/ml oral solution.

There are concerns the crystals could block feeding tubes in patients who receive the medicine this way. 

Affected batch numbers - all of which are 150ml pack sizes - include 09E1 and 11E1, which were first distributed on November 12, 2025, with an expiry date of October 1, 2026. 

The issue was identified after officials received a customer complaint, and affects a further five batches.

This includes 12E1 and 13E1, first distributed on January 2, 2026, with an expiry date of December 1, 2026. 

Also affected are 14E1, first distributed on January 20, 2026, and expiring on December 1, 2026; batch 19F1, first distributed on April 8, 2026, and expiring on March 1, 2027; and batch 21F1, first distributed on May 12, 2026, and expiring on April 1, 2027. 

The MHRA says the crystals do not affect the potency of the medicine, but have advised healthcare professionals to inspect bottles before dispensing them and return any that contain visible crystals. 

It adds that alternative formulations should be considered when the drug is administered through feeding tubes - such as nasogastric or percutaneous endoscopic gastrostomy - because crystals could potentially cause obstruction.

However, no recall has been issued because the medicine is considered critical to supply.

Manufacturer Relonchem claims the affected batches remain safe for patients to use. 

Those who notice crystals in their bottle have been instructed to contact a medical professional but should not stop taking gabapentin unless advised to do so by their doctor.

Officials said people taking the drug should store it at room temperature - below 25C and ideally above 15C - and should not refrigerate or freeze it. 

The MHRA said: 'Never stop taking medicines such as gabapentin without medical advice. Suddenly stopping a medicine used for epilepsy, may cause your seizures to start again or happen more often or last longer than before. 

'Suddenly stopping gabapentin when used for pain may impact your pain control.

'Patients who have any additional concerns related to this information should contact their pharmacist in the first instance.

'Patients who experience adverse reactions or have any questions about their medication should seek medical attention. 

'Any suspected adverse reactions should also be reported via the MHRA Yellow Card scheme.'

Gabapentin is one of two main medicines in a class known as gabapentinoids, which are commonly used to treat nerve pain. The other is pregabalin. 

More than 4.5million people in England are prescribed a gabapentinoid each year, most commonly in the form of gabapentin or pregabalin. 

Gabapentin is best known in the UK under the brand name Neurontin, although it is also available as generic medicines manufactured by companies including Sandoz, Accord and Glenmark.  

The medicine is available as tablets, capsules and an oral liquid solution, which may be preferred by some patients who have difficulty swallowing solid medicines.