Voltaren and other forms of diclofenac carry a risk of cardiovascular events including heart attacks and strokes, Medsafe has warned.
Medsafe - the Ministry of Health's medicines safety authority - said diclofenac was a non-steroidal anti-inflammatory drug used for the relief of moderate pain and inflammation.
Recent publications had suggested an increased risk of cardiovascular events such as heart attack and stroke with the use of the drug, Medsafe said.
Non-steroidal anti-inflammatory drugs - including diclofenac - were safe and effective at relieving pain and inflammation for most people.
However, smokers, those with high blood pressure, high cholesterol, diabetes, or poorly functioning kidneys should check with their healthcare professional that the medicine was appropriate, Medsafe said.
Consumers were advised to use the lowest dose that worked for them, and to stop as soon as they could.
Medsafe and the Medicines Adverse Reactions Committee (MARC) said there was a very small increased risk of these effects with diclofenac, when used at high doses and for long-term therapy.
Study limitations made it impossible for Medsafe to determine whether there was a higher risk of cardiovascular events with diclofenac treatment compared to treatment with other non-steroidal anti-inflammatory drugs.
Diclofenac is available under different brand names including Apo-Diclo, Diclax, Diclofenac and Voltaren.
The warning applied to diclofenac tablets, suppositories and injections, but not products applied to the skin or used in the eye.
Medsafe said as they could not give advice about an individual's medical condition, anyone with concerns should talk to their healthcare professional.
The safety authority advised they were working with the sponsors of diclofenac products to ensure data sheets, consumer medicine information and package inserts appropriately outlined the safety of the drug.