Paracetamol and keeping active are the best cures for back pain, according to Australian researchers who warn that other treatments do not work.
Acute low back pain is very common
A Lancet study of 240 back pain sufferers found anti-inflammatory drugs and spinal manipulation did not make any difference to recovery time.
Yet currently, both treatments are recommended in several guidelines.
Experts said patients needed to be reassured that avoiding bed rest and taking paracetamol would work.
Researchers at the University of Sydney assigned patients to receive either an anti-inflammatory drug called diclofenac, a dummy drug, spinal manipulation or fake manipulation therapy.
They had already received simple treatment advice from their GP to keep active, avoid bed rest and take paracetamol for the pain.
The study found no difference in recovery times after 12 weeks in patients who also received diclofenac or spinal manipulation.
Almost all the patients had recovered by the end of the study no matter what treatment they had received.
Study leader Mark Hancock said there was no clinical benefit from the additional treatments.
And both non-steroidal anti-inflammatory drugs (NSAIDs), such as diclofenac or ibuprofen, and spinal manipulation are associated with adverse effects, he added.
"GPs can manage patients confidently without exposing them to increased risks and costs associated with NSAIDs or spinal manipulative therapy," he said.
Dr Bart Koes from the Department of General Practice at Erasmus University in the Netherlands, who wrote an accompanying article in The Lancet, said the results were probably applicable to other non-steroidal anti-inflammatory drugs, such as ibuprofen.
He told the BBC: "It is very likely that for many patients with acute low back pain currently treated with NSAIDs and/or spinal manipulation this would not have been needed if adequate first-line treatment with paracetamol and advice and reassurance was given."
Dr Stuart Derbyshire, senior lecturer in the School of Psychology and expert in pain at the University of Birmingham, also agreed with the findings.
"For most people, providing simple care and advice should guide the patient through their acute phase of pain and allow them to return to normal life when that acute phase is over."
Back pain is the largest single cause of sickness absence from work.
But Tony Metcalfe, president of the British Chiropractic Association warned the therapy in the study could not be compared with the treatment provided by chiropracters in the UK.
"Spinal manipulation is just part of a package of care offered by BCA chiropractors which also includes lifestyle and posture advice, rehabilitation and specific exercises."
He added that spinal manipulation therapy is a safe treatment and none of the study participants reported serious adverse reactions.
Nia Taylor, chief executive of BackCare said the key message for people was to keep moving.
"We know that many GPs feel ill-equipped to help patients with low back pain and sometimes people are not given the right advice and reassurance when they first see a GP."
She added: "In the UK a standard appointment of 10 minutes may not be long enough to give adequate advice and reassurance and convince the patient that a regime of paracetamol and keeping active is enough to ensure recovery."