Medically reviewed by Debra Sullivan, Ph.D., MSN, R.N., CNE, COI — Written by Amanda Barrell on December 2, 2020
Many people experience smelly armpits from time to time. When people sweat, the liquid mixes with the bacteria on the skin. When this dries, it can cause an unpleasant smell.
Several remedies are available for excessive sweating, including over-the-counter treatments, prescription medications, injections, and more.
In this article, we look at what causes smelly armpits, how to treat them, and when it might be a good idea to speak with a doctor.
Causes
Sweat is responsible for smelly armpits. Sweating is a normal and necessary bodily function that stops people from overheating.
There are 2–4 million sweat glands on the body. Most of these are eccrine sweat glands, and the others are apocrine sweat glands. People have lots of both types of sweat gland in the armpits.
When a person exercises or becomes too hot, the sweat glands release sweat, which evaporates and cools the body down. Stress and intense emotions can also make people sweat.
Eccrine glands release a clear liquid that does not smell. However, if it dries on the skin, it can smell.
Apocrine glands release a thick fluid that smells when it mixes with the bacteria on the skin.
The sweat glands become more active in both males and females during puberty. As a result, it is common for teenagers to start to get smelly armpits when they did not before.
Some people have a medical disorder that makes them sweat more than they should. The name for this condition is hyperhidrosis.
Hyperhidrosis affects about 3% of the population. People who have the disorder have overactive sweat glands that release sweat even when they are not hot or exercising.
Hyperhidrosis is usually harmless, but it is sometimes the result of an overactive thyroid.
When sweat mixes with bacteria, it can lead to a distinctive body odor, which people commonly refer to as B.O. If this odor becomes chronic, doctors call it bromhidrosis.
Some foods, such as garlic, can change the way sweat smells.
Treatments
Good hygiene can help prevent smelly armpits by getting rid of the bacteria that cause the odor.
People should shower or bathe once a day and after exercise. They should also wear clean clothes every day and change their clothes after exercising.
As well as practicing good hygiene, people can try other ways to combat smelly armpits. These include:
Antiperspirant
Shaving the armpits and using a deodorant or antiperspirant can often help prevent body odor. Regular deodorant comes with a fragrance that will help mask the smell.
Antiperspirant contains chemicals that stop people from sweating. They plug the sweat glands, which tells the body to stop making sweat.
These simple measures might not work for people with hyperhidrosis.
If sweating is excessive, it can cause smelly armpits even if a person washes regularly and uses deodorant or antiperspirant.
The first thing that a doctor will recommend is usually a prescription strength antiperspirant. Sometimes, these might burn or irritate the skin. If this happens, the person should tell their doctor.
If prescription strength antiperspirants do not stop the excessive sweating, doctors might suggest the treatments below.
Botulinum toxin injections
People usually refer to botulinum toxin injections as Botox.
Sometimes, doctors inject tiny amounts of Botox into the armpits to treat excessive sweating.
Botox injections help stop excessive sweating by blocking a chemical in the body that stimulates the sweat glands.
For most people, it takes 4–5 days to work, and the effects usually last for about 4–6 months.
Some people might find the injections painful.
Prescription medication
If excessive sweating affects the whole body, doctors might suggest using anticholinergic medicines.
Anticholinergic medicines stop people from sweating, so they are not generally suitable for athletes or people who live in hot climates.
Common side effects of these drugs include:
Sudden changes to body odor
Eating some foods, including garlic and onion, can make sweat smell different. Alcohol can also have this effect. Consuming certain foods and drinks may, therefore, lead to a sudden change in body odor around the armpits.
Stress and anxiety can make people sweat more than usual. Sometimes, this can lead to a sudden change in the way the armpits smell.
Many different factors can cause what doctors call secondary hyperhidrosis. This term means that the excessive sweating is a symptom of something else.
Possible causes of secondary hyperhidrosis include:
- Menopause: People who have been through menopause can develop hyperhidrosis afterward. Doctors might recommend hormone replacement therapy or anticholinergic medications.
- Medicines: A change in body odor might be a side effect of a medication. Opiates, such as methadone, and cholinergics, such as galantamine, can have this effect. Taking selective serotonin reuptake inhibitors (SSRIs) — a type of antidepressant — or multiple medications can also lead to hyperhidrosis.
- Infections: Some infections, including brucellosis, HIV, malaria, and endocarditis, can lead to secondary hyperhidrosis.
Excessive sweating is not necessarily the cause of all sudden changes in armpit odor.
For instance, the skin condition intertrigo might cause a musty smell. This condition, which causes a rash, develops in folds of the skin, such as those in the belly, under the breasts, and in the armpits.
Doctors might recommend using a special soap that contains 1% ketoconazole. They will also suggest keeping the affected area as clean and dry as possible.
When to see a doctor
Everyone will have smelly armpits from time to time. It is perfectly normal and not typically a cause for concern.
If smelly armpits are a more frequent occurrence, though, they can get in the way of everyday life.
Both hyperhidrosis and bromhidrosis can cause distress and social problems. When this is the case, the person should speak to a doctor.