Journal of Alternative and Complementary Medicine
J Altern Complement Med. 2014 Apr 1; 20(4): 219–220.
PMCID: PMC3995208
1Department of Clinical Biomedical Science, Charles E. Schmidt College of Medicine, Florida Atlantic University, Boca Raton, FL.
2Department of Preventive Medicine, Nova Southeastern University, Fort Lauderdale, FL.
3Department of Family and Community Medicine, University of Miami Miller School of Medicine, Miami, FL.
Corresponding author.
Address correspondence to:, Charles H. Hennekens, MD, DrPH, Sir Richard Doll Professor, Charles E. Schmidt College of Medicine, Florida Atlantic University, 2800 S. Ocean Blvd., PHA, Boca Raton, FL 33432, E-mail:Email: ten.ygidorp@DMHHCFORP
In the United States—indeed,
throughout the world—low back pain is a major clinical and public
health problem. With a lifetime prevalence of about 84% for low back
pain and a prevalence of 23% for chronic low back pain (CLBP)1, low back pain is a major cause of morbidity, especially with respect to work days lost.2 In fact, the prevalence of disability as a result of low back pain is 11% to 12%.1
The economic burden arising from this clinical and public health
problem is large and continues to grow. In the United States, for
example, total direct costs of healthcare utilization related to low
back pain are estimated to be $96 million a year.3
At
present, nonsteroidal anti-inflammatory drugs (NSAIDs) are the major
pharmacologic therapies used for the relief of inflammation accompanying
CLBP in patients with symptoms that cannot be attributed to a specific
disease or spinal abnormality. NSAIDs include traditional NSAIDs, such
as naproxen, and cyclooxygenase 2 inhibitors, known as coxibs. In a
recently published, comprehensive worldwide meta-analysis 4
of randomized trials, the vascular and upper gastrointestinal risks of
traditional NSAIDs and coxibs were compared and contrasted. The vascular
risks of high-dose diclofenac were comparable to those of the coxibs,
while high-dose naproxen was associated with less vascular risk than
other NSAIDs, including the coxibs. It should be noted that proportional
effects on major vascular events were independent of baseline
characteristics, including vascular risk factors. All NSAID regimens
doubled the risk of heart failure and increased the risk of upper
gastrointestinal complications, although coxibs and diclofenac were
somewhat less gastrotoxic than ibuprofen and naproxen. Since naproxen is
the only drug in this class that provides symptomatic relief of pain
and inflammation with no increased vascular risk, it is likely to be
more widely used despite the substantial gastrointestinal risks
accompanying its use.
In addition to the cardiovascular
and gastrointestinal risks they present, traditional NSAIDs and coxibs
offer only limited benefits for the treatment of low back pain. A
systematic review of randomized trials of patients with acute low back
pain and CLBP showed that NSAID use by patients with acute low back pain
brought about an average short-term improvement of only 8 points on a
0-to-100 scale compared to placebo use. NSAID use by patients with CLBP
brought about an average short-term improvement of only 12 points
compared to placebo use.5 Furthermore, no one drug in this class had any greater benefit on pain than any other.5 Given this, other remedies for low back pain need to be explored. Two topical herbal remedies, Capsicum frutescens (cayenne or capsaicin) and a combination of Gaultheria procumbens (wintergreen oil) and Menthe piperata
(peppermint oil) offer plausible alternative therapies to NSAIDs and
coxibs and the potential for a greater benefit-to-risk ratio.
Capsaicin is a powerful local stimulant that, with repeated applications, leads to persistent desensitization to pain.6
In some clinical practices, topical capsaicin is used extensively for
the treatment of CLBP. The scientific rationale for its use is derived
from the results of three randomized placebo-controlled trials, one of
acute mechanical back pain and two of chronic nonspecific back pain.7
In each of these trials, the use of topical capsaicin produced
statistically significant reductions in pain compared with the
reductions in pain with the use of placebo. In a subsequent review 8
of two of the three randomized, placebo-controlled trials of CLBP,
capsaicin produced a statistically significant 60% reduction in pain. It
should be noted that the risks of topical capsaicin are generally mild
and usually limited to local reactions in about one third of the treated
patients.6
The
predominant natural ingredient in wintergreen oil is methyl salicylate,
which is a compound closely related to acetylsalicylic acid, or
aspirin. When applied to the skin, including tissues at the site of
pain, wintergreen oil has analgesic properties. However, due to its
aspirin-like qualities, the possibilities and potential, in theory, for
bleeding and other side effects must be considered. A combination of
wintergreen oil and peppermint oil is commonly used because it is
believed to give far better pain relief than either wintergreen oil or
peppermint oil alone. In addition, the combination of the two oils may
potentiate the individual effects of each oil, thus enabling the use of
lower doses of each, which, as a consequence, is likely to produce fewer
side effects. At present, wintergreen oil is used far less frequently
than capsaicin, at least in part because there are no published
randomized trials comparing wintergreen oil or a combination of
wintergreen oil and peppermint oil to placebo for low back pain.
Consequently, the available totality of evidence is wholly insufficient
upon which to judge the benefits and risks of these topical remedies. In
particular, data are lacking from randomized trials designed a priori to test the hypothesis which may be related to perceived concerns about the safety of methyl salicylate.9
In fact, however, if 10 ml of a 2.5% formula of wintergreen oil were to
be applied all at once to the skin and totally absorbed, the dose would
represent the same amount of salicylate present in one 325 mg aspirin
tablet.10
Many methyl salicylate-containing products are available over the
counter and self-medication produces very few side effects. There are no
safety issues with high quality Gaultheria procumbens. The perception of Gaultheria procumbens safety issues has arisen from the use of inferior quality or adulterated wintergreen-like oils.
The
clinical challenges for healthcare providers who treat CLPB should be
viewed as a major challenge to researchers, a challenge to compare the
benefits and risks of these potentially promising and safer alternative
treatments to conventional therapies. Topical capsaicin and wintergreen
oil or a blend of wintergreen and peppermint oils as treatments for CLBP
are likely to have far fewer side effects than conventional therapies.
To the best of our knowledge, however, none has been directly tested
against traditional NSAIDs and coxibs in randomized trials. If
wintergreen oil or the blend of wintergreen and peppermint oils were
demonstrated to be equivalent or superior to NSAIDs, then the topical
agent of greatest efficacy may need to be more widely used in clinical
practice. If capsaicin were shown to be less effective than NSAIDs in
randomized trials then this result should inform clinical practice.
Finally, it is important to discern whether there are additive benefits
and/or risks to these oral and topical herbal remedies for CLBP.
Author Disclosure Statement
Drs.
Hebert and Barice report no competing financial interests. Professor
Hennekens reports that he is funded by the Charles E. Schmidt College of
Medicine at Florida Atlantic University, where he serves as senior
academic advisor to the dean of the College of Medicine. He also acts as
an independent scientist in an advisory role to investigators and
sponsors and as an independent scientist in an advisory role to legal
counsel for GlaxoSmithKline and Stryker. He is a chairperson or member
of the data and safety monitoring boards for Actelion, Amgen,
AstraZeneca, Bayer, Bristol-Myers Squibb, British Heart Foundation,
Canadian Institutes of Health Research, Lilly, and Sunovion. He also
serves as an independent scientist in an advisory role to the U.S. Food
and Drug Administration, U.S. National Institutes of Health, Children's
Services Council of Palm Beach County, and UpToDate. He receives
royalties for authorship or editorship of three textbooks and, as a
co-inventor, for patents, held by Brigham and Women's Hospital, dealing
with inflammatory markers and cardiovascular disease. He has an
investment management relationship with the West-Bacon Group within
SunTrust Investment Services, which has discretionary investment
authority. Professor Hennekens does not own any common or preferred
stock in any pharmaceutical or medical device company.
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