By LOUISE CARR, Associate Editor and Featured Columnist
You expect to sweat and smell a little when it’s hot, when you’ve been working out, or you’re nervous – especially in the underarm region. Underarm odor may simply be a sign of questionable hygiene, or the mark of a busy day. But could your underarm odor actually signal something more serious?
Has your underarm odor – called "osmidrosis" or "bromhidrosis" – changed dramatically recently?
Do your underarms smell like apples or even rotting fish?
You may be surprised to learn that some diseases and health conditions can change the way you smell.
In fact, a 2014 study from the Karolinska Institutet in Sweden shows that the human nose is actually able to smell sickness in a person whose immune system is highly active – some diseases actually have particular smells.
Take a sniff under your arms and you might just diagnose something serious.
Why Do We Get Underarm Odor?
Body odor is a nasty-smelling condition which occurs when the bacteria on your skin multiply in ideal conditions – when you sweat – and start to break down skin proteins. The odor can be particularly strong in the underarm region.
Body odor is a fact of life and it happens all the time, to pretty much everyone, when you sweat. Sweat is actually odorless but the type of sweat you produce in your armpits (along with your groin) smells bad when it combines with the bacteria that normally live on your skin.
Underarm odor varies from person to person, from day to day, and is affected by the amount of sweat, hygiene practices, and stress. Changes in underarm odor can also be a sign of a medical problem.
When Does Underarm Odor Signal a Problem?
For most people, sweating and smells from the underarms are completely normal. For most people, underarm odor doesn’t necessarily signal anything and can be removed by washing and keeping sweat levels down.
But for some people, underarm odor is harder to get rid of.
For example, hormones can cause body odor changes. Women going through the menopause sweat more, which results in a different or stronger underarm smell.
Strange underarm odors can also be a sign of stress. When you are stressed you sweat more, and body odor becomes more pronounced.
Also, certain medical conditions affect body odor, including diabetes, cancer, genetic diseases, and kidney and liver problems.
Do Spicy Foods and Alcohol Change your Underarm Odor?
As well as certain medical conditions, other popular beliefs exist that certain foods can cause strange underarm odors.
Can curry affect your body odor? What about garlic?
No authoritative studies have been completed into the issue but experts believe that because components in aromatic spices and herbs are fat soluble, they get stored in your body fat and will travel into your sweat, so could influence the smell of your underarms.
In terms of alcohol, some will inevitably seep out through the pores so your underarms may smell more after you’ve drank a lot.
If your underarms smell unusual, we looked at the medical conditions that could cause the change of scent.
1. Bad Armpit Smells May Be Caused by Breast Cancer
A gene responsible for breast cancer causes bad smelling armpits and excess earwax, a 2009 study from the Tokyo Institute of Technology.
Scientists discovered a distinct link between the gene associated with breast cancer and excessively smelly armpits and wet, sticky ear wax.
These could be lifesaving clues when it comes to detecting cancer before it progresses.
2. Trimethylaminuria Can Change the Way Your Underarms Smell
A rare disease called "trimethylaminuria", which affects only one on every 200,000 people could be the cause of strange-smelling underarms.
The Genetics Home Reference at the National Institutes of Health says that metabolic diseases like trimethylaminuria give odor a different scent – in this case, it can cause underarms to smell like rotting fish or garbage.
The genetic condition happens when the body is unable to metabolize trimethylamine in the gut. An excess builds up, producing a fishy odor. In fact, trimethylamine is what gives fish its distinctive smell.
Scientists in a 2011 study from the Monell Chemical Senses Center say that up to one third of patients with unexplained body odor test positive for trimethylaminuria.
3. Lung Cancer Tumors Can Cause Changes in Underarm and Body Odors
A 2010 study from the Monell Chemical Senses Center demonstrates that lung cancer tumors can cause changes in body odors that can be detected by trained animal sensors and sophisticated chemical processes.
The researchers say that this kind of underarm odor sensing could vastly improve detection rates for early lung cancer.
4. Diabetes Changes Underarm Odor
One of the more common causes of underarm odor is diabetes.
If you suffer from diabetes you are at risk of "ketoacidosis", a condition that occurs when you do not properly monitor and care for blood sugar levels.
Ketoacidosis causes a fruity smell on the breath as well as a pungent body odor.
A 2016 study from National Taiwan University says that integrative Traditional Chinese Medicine can reduce the risk of ketoacidosis in people with type 1 diabetes.
The researchers found that people using this type of medicine were 33 percent less likely than others with diabetes to suffer from ketoacidosis.
5. Hyperhidrosis is a Cause of Bad Underarm Odors
According to recent research, 2.8 percent of the population in the US suffers from excessive sweating, called hyperhidrosis. The 2004 study from Saint Louis University reveals that the condition affects a much larger proportion of the population than previously thought – up to 17.8 million people. Out of this number, 4 million suffer from excessive sweating of the underarms.
Hyperhidrosis causes excessive sweating on the underarms, the palms of the hands, the feet, and the face.
With excess sweat comes more odor as the conditions are better for bacteria to thrive.
6. Liver and Kidney Problems May Result in Underarm Odor
Bad underarm odor may be caused by liver or kidney dysfunction, as when these organs do not do their job, toxins are not effectively removed from the body.
This can create an odor. A 2014 study from the Technion-Israel Institute of Technology, Haifa, Israel says that kidney injury can be detected early by breath samples.
7. Can Underarm Odor Really Reveal Malarial Infection?
Infection with malaria changes the scent of infected mice, according to a 2014 study from ETH Zürich and Pennsylvania State University.
If the malaria infection is present, the infected mouse’s scent is particularly attractive to mosquitoes, experts say.
The researchers believe that it is logical that infected humans also smell more attractive to mosquitoes – but that these smells may not be detectable by the human nose.
Nevertheless, there is scope for research into an early screening test that could catch the presence of malaria when there are no other symptoms present.