Every evening, German televisions showcase a dog and cat, shocked to see their owners suddenly free of pain and as agile as in their young age. The reason: various creams. But most probably, this is not the case. Pain creams do not work better than placebo, according to a study.
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Despite the lack of suitable studies on the efficacy of topical pain creams, sales of such products have increased exponentially in recent years alone. Topical analgesics are particularly popular with chronic pain patients and are very popular due to their direct effect at the site of pain and their simple application.
A recent study has looked into the question of whether the preparations really deliver what they promise. The researchers examined 133 people with neuropathic pain, 133 others with nociceptive pain and 133 patients with mixed pain causes.
The patients with neuropathic pain received pain creams based on ketamine, clonidine, and lidocaine. Nociceptive pain patients, on the other hand, received cyclobenzaprine and lidocaine. The third (mixed) group used e.g. ketamine, diclofenac, cyclobenzaprine or lidocaine. The results were compared with a placebo treatment.
The primary endpoint of the study was the change in the average pain score after one month of treatment with the respective topical analgesic. The results were both surprising and clear.
In all treatment groups, the pain score decreased by only -0.1 to -0.3 points. After one month of therapy, a total of 72 patients (= 36%) from the treatment groups reported a perceived improvement in pain symptoms. In the same period, 54 patients (= 28%) from the placebo control said the same. So the analgesics didn't work any better than a placebo.
It should be considered that the significance of the study results is limited due to the heterogeneous treatment regimes with a large number of active substances, but also due to the short observation period of only one month. On the other hand, however, this study once again shows that topical pain medications are probably highly ineffective, especially in chronic pain patients.
On this basis, the use of topical analgesics for chronic pain patients must at least be critically questioned. The sometimes high costs for long-term therapy appear unjustified against the background of a lack of proof of efficacy beyond the placebo effect.
Brutcher RE et al., Ann Intern Med. 2019; DOI: 10.7326/M18-2736