Health authorities are urgently investigating problems with a drug taken by 70,000 New Zealanders after a rash of reports of nausea, headaches and weight gain.
Head of Medsafe Stewart Jessamine said today there had been a surge of reports to the drug safety agency's Centre for Adverse Reactions Monitoring for the drug Eltroxin, which is used to treat hypothyroidism.
Patients were complaining of nausea, sore eyes, tenderness, various aches and in some cases weight gain.
Dr Jessamine said people on the drug should not stop taking it, but anyone experiencing side effects should contact their GP.
The drug was reformulated by manufacturer GlaxoSmithKline (GSK) a year ago and as a result instructions on how it should be taken had changed.
Up until the last few weeks there had been few complaints, despite the drug being dispensed since July and the same reformulation had been used in Germany for 18 months without problems.
Dr Jessamine said Medsafe was considering the possibility there was a problems with the current batch of the drug available in New Zealand.
However it was also retesting the drug itself and investigating patients' specific complaints.
National MP Jackie Blue, a breast physician, today questioned health officials attending Parliament's health committee about what they were doing in regard to the "hundreds of people reporting serious side effects".
She also asked whether there were alternatives they could turn to if they were experiencing problems.
Dr Jessamine said as well as the various tests the agency was running it had now required the company to issue information about the reformulation and altered instructions on how to take it three times.
The first two times were to doctors and pharmacists, but it had now taken the unusual step of ordering the company to send out information direct to consumers as anecdotal reports suggested a lot of patients were ignorant of the changes.
Unlike the previous formulation, the new one needed to be taken on an empty stomach and pills should not be split in half.
Dr Jessamine said there was no other subsidised product containing thyroxine - Eltroxin's active ingredient - in New
Zealand, meaning patients had no other cheap choice to turn to.
However Medsafe was working with GSK to see if they could make a different formulation available.
He said appropriate tests were done on the reformulated product before it was dispensed.
He said there had been an upsurge in adverse reports in the past week, since advertisements were run in newspapers and some coverage in regional media.
Hypothyroidism is a condition where the thyroid gland does not produce enough hormones, leading to fatigue and in some cases depression.
NZPA