Foul Odor From the Body: Causes by Location

Foul odor by location: what it can mean

Common causes of foul odor

Breath

Most bad breath starts in the mouth. Bacteria on the back of the tongue and in gum pockets release sulfur gases. Gum disease, food trapped between teeth, dentures, tonsil stones, smoking and a dry mouth are the main causes. Less often, bad breath comes from sinus infections, reflux, or rarely from diseases elsewhere in the body.

Vaginal odor

A mild natural scent is normal and changes through the menstrual cycle. A strong fishy smell, often worse after sex or during a period, is the classic sign of bacterial vaginosis, an imbalance of vaginal bacteria. Trichomoniasis, a sexually transmitted infection, causes a foul odor with frothy discharge. Yeast infections usually do not smell much. Douching and scented washes disturb normal bacteria and make odor worse.

Body odor (BO)

Sweat itself is almost odorless. Odor appears when skin bacteria break down sweat from the apocrine glands in the armpits and groin. It is worse after puberty, in hot weather, with tight synthetic clothing, and with some foods such as garlic, onions and curry spices. Heavy sweating (hyperhidrosis) increases it.

Wounds and skin

A bad smell from a wound suggests bacteria growing in it, often with increasing pain, redness, warmth and pus. Chronic wounds such as leg ulcers and diabetic foot ulcers can smell even when well managed. Hidradenitis suppurativa causes recurring painful lumps and draining tunnels in the armpits and groin with a foul-smelling discharge.

Stool and gas

Some odor is normal. Stools that are suddenly far more foul than usual, greasy, pale and float may mean fat is not being absorbed, as in celiac disease, chronic pancreatitis or giardia infection. Bloody, foul diarrhea needs prompt assessment.

Metabolic and rare causes

• Diabetic ketoacidosis: fruity breath from ketones.
• Kidney failure: ammonia or fishy breath.
• Liver failure: a musty, sweet breath called fetor hepaticus.
• Trimethylaminuria ("fish odor syndrome"): an inherited inability to break down a compound in foods, causing a fishy smell in sweat, urine and breath.

When the smell is only in your nose

If you smell something foul that others cannot, the problem may be in your sense of smell. Phantosmia (smelling phantom odors) and parosmia (normal smells seeming rotten) are common after COVID-19 and other viral infections, and can follow head injuries or sinus disease. Rarely they are linked to migraine, seizures or brain tumors.

How doctors find the cause

A doctor will ask where the smell comes from, how long it has been present, whether there is discharge, pain or fever, and about diet, hygiene, medicines and sexual history. Examination of the area is the main step. Tests may include a vaginal swab, urine test, wound swab, stool tests, blood sugar or ketone testing, or kidney and liver blood tests.

Treatment

Treatment follows the cause:

• Breath: brush twice a day, clean between teeth daily, brush or scrape the tongue, stay hydrated and see a dentist for gum disease.
• Body odor: wash daily with soap, especially the armpits and groin, dry thoroughly, wear breathable fabrics and use an antiperspirant. Prescription-strength antiperspirants help heavy sweating.
• Vaginal odor: avoid douching and scented products. Bacterial vaginosis and trichomoniasis need prescription treatment, and partners are treated for trichomoniasis.
• Wounds: cleaning and dressing, antibiotics for infection, and removal of dead tissue by a clinician.
• Medical causes: treating diabetes, kidney or liver disease, or malabsorption.

Frequently asked questions

What causes a sudden foul body odor?

A sudden change can follow a new diet, medicines, hormonal changes, heavier sweating or stress. A localized new smell often points to infection, such as bacterial vaginosis or an infected wound. A fruity or ammonia-like smell on the breath can signal diabetes or kidney problems and needs a medical check.

What does a foul odor from a wound mean?

It usually means bacteria are growing in the wound, especially with redness, warmth, swelling, pus or increasing pain. Rapidly spreading redness, dark skin or severe pain needs emergency care. Some chronic ulcers smell even when cared for properly, but any new or worsening odor should be checked.

Why does my discharge have a foul smell?

Foul-smelling vaginal discharge is most often from bacterial vaginosis (fishy odor) or trichomoniasis. A forgotten tampon causes a very strong smell. Foul discharge with fever or pelvic pain may mean pelvic infection. A doctor or clinic can test a swab and prescribe treatment.

Can illness change how you smell?

Yes. Uncontrolled diabetes can cause fruity breath, kidney failure an ammonia smell, and liver failure a musty breath. Some infections change the smell of urine, stool or wounds. A persistent unexplained change in body odor is worth mentioning to your doctor.

Why do I smell a bad odor that no one else smells?

This is called phantosmia, smelling an odor that is not there. It often follows viral infections including COVID-19, sinus problems or head injuries, and usually improves over months. Persistent phantom smells, especially with headaches or other neurological symptoms, should be evaluated by a doctor.