Doctors in Greater Manchester have been advised not to prescribe homeopathy by the region's NHS medicine decision-making body.
The Greater Manchester Medicines Management Group said "no clear evidence" had been found that homeopathy was beneficial.
It has written to all 10 NHS trusts advising them not to prescribe, refer or recommend homeopathy to patients.
The Society of Homeopaths said the advice was "based on inaccurate" data.
The recommendation came after the Department of Health told Primary Care Trusts last month that they could decide whether or not to fund homeopathy.
Doctors at the British Medical Association annual meeting agreed with a government report that homeopathy should not be paid for by the NHS and that training posts in homeopathic hospitals should be scrapped after findings that it was no more beneficial than a placebo.
A spokesperson for NHS Manchester said the advice supported the action of most GPs in the city.
"It's a rarity for GPs to prescribe homeopathy and the existing practice of not prescribing it has really just been formalised by this recommendation."
A spokesperson for the Society of Homeopaths said: "We fully endorse the Department of Health's stance which is to support patient choice, and is sorry to see Greater Manchester Medicines Management Group limiting patient choice based on inaccurate information.
"The Society is aware of patient demand for homeopathy, and respects patients' capacity to make informed choices about their healthcare."