It's completely fine to have bad breath when you wake up in the morning, if you've recently eaten a pungent food (like onions), or if you've gone a few hours without brushing your teeth.

If the odor sticks around, though, or seems particularly strong, a health issue may be to blame. "If bad breath does not resolve with tooth brushing or using mouthwash, you may need further evaluation for tooth decay and gum disease by your dentist," Seema Sarin, MD, an Internal Medicine Physician at EHE, tells Bustle. "Other causes of foul breath odor may be upper or lower respiratory illnesses and disease including sinusitis, throat infections, or lung infections."

When an infection is afoot, the smell of the bacteria can travel up from your lungs or throat, and lead to bad breath that isn't cured by oral hygiene alone. By letting your doctor know, they can treat the underlying cause, and help you feel better.

Some people experience a sweet scent on their breath, that isn't necessarily bad smelling. But since it can potentially be a sign of diabetes, it's a good idea to point it out to a doctor.

"When you notice a fruity smell on someone’s breath similar to acetone, it could be a sign that blood sugar levels are elevated indicating diabetes or diabetic ketoacidosis, a condition in which your body begins to convert the excess sugar in your bloodstream to ketones," Dr. Rose says. "This can also occur in fasting and high-protein diets."

Most foot odor can be chalked up to basic hygiene. After taking a shower and giving them a scrub, your stinky feet will likely be good as new. But if the odor persists, it may be a sign something else is going on, such as a fungal infection.

"Yeast, fungus, mildews, and some bacteria like to live in warm, moist, dark environments and they can grow in the shoes," board-certified dermatologist Tsippora Shainhouse, MD, FAAD, tells Bustle. "However, if the smell persists, and/or if you see rashes, dry scales on your feet, or if you notice thick, yellow, or crumbling toenails, see your dermatologist to check for a fungal infection on your feet and/or nails, which can be treated with anti-fungal medications."

All vaginas have an odor, to one degree or another, and that's a-OK. It is important, however, to see a doctor if the scent changes, or if it becomes stronger than usual, as it may be a sign of an infection.

"A foul odor or smell coming from your vagina could be a sign of infection and should be checked out by your friendly OB/GYN," Dr. Angela Jones, Astroglide’s resident sexual health advisor, tells Bustle. "Infection could be something like yeast, bacterial vaginosis, or a sexually transmitted infection."

For bacterial vaginosis in particular, you might notice a "fishy" smell. "An unusual, fishy smell coming from your vagina could be a sign of bacterial vaginosis, a condition in which your normal vaginal bacteria and vaginal pH changes," Dr. Rose says. "This could result from using fragranced tampons, douching or washing with soap, or having to take a round of antibiotics. This condition may also present with a discharge which would also be a sign to see your doctor for an assessment."

By paying attention to these changes in your body, and seeing a doctor about them ASAP, you can treat the underlying problem before it gets worse — and get back to feeling like yourself again.

Everyone passes gas — especially after eating — so no worries if you need to fart throughout the day, or if you occasionally feel bloated. And don't assume the worst if it doesn't smell great, either, as gas rarely does.

You may want to see a doctor, though, if you're passing gas more often than usual, or if it smells particularly rank. "If you notice that your gas smells worse than usual, or is more frequent or severe — particularly if it is associated with abdominal bloating or cramping or a change in bowel habits — see you doctor to rule out an underlying condition, including food intolerance (dairy, gluten, FODMAPS), SIBO (small intestine bacterial overgrowth), irritable or inflammatory bowel disease, liver or pancreatic disorders," Dr. Shainhouse says.

Just like gas, you certainly can't expect your armpits to smell super great. Throughout the day, your natural sweat (which is odorless) will combine with the bacteria on your skin, so a few hours after showering, you may notice that you have some odor. No big deal.

Some folks, though, have a condition known as bromhidrosis, which is the technical word for smelly sweat or body odor that just won't go away — even after showering or applying deodorant.

"It is a combination of the fatty acids and testosterone precursors produced in apocrine sweat glands in combination with skin bacteria, which produce enzymes that break down the fatty acids to smaller, smelly molecules," Dr. Shainhouse says. "Certain fatty acid plus bacteria combinations can produce specific odors. Super-sweaty areas, like armpits, are a major breeding ground for bacteria on both the skin and in the hair follicles. The most common sites of body odor include the armpits, genitals, areolae, and navel (belly button), all of which have apocrine glands."

It can be an upsetting condition, but never fear. "If the [odor] just doesn’t resolve or you have excessive sweating, see your dermatologist to discuss other prescription treatment options," Dr. Shainhouse says.

Everyone has their own unique smell, when it comes to their scalp and hair. And usually, the scent of your hair is nothing you need to think twice about.

But if you notice a change in the odor of your scalp — even after you shampoo — it may be worth telling your doctor about, so they can look into the reason why.

"If the condition persists, despite more frequent washing, see your dermatologist to rule out a skin condition, including seborrheic dermatitis or even a bacterial or fungal infection," Dr. Shainhouse says.

According to WebMD, seborrheic dermatitis — known more commonly as "dandruff" — is a skin disease that looks similar to psoriasis, eczema, or an allergic reaction. It can appear on your body as well as your scalp and is usually harmless, but can be incredibly itchy. So if it's bothering you, let your dermatologist know.

There's nothing wrong with body odor in general. As long as you're in good health, giving off the occasional scent is nothing to worry about. You should, however, pay attention to new, strong, or persistent body odors, as they may be your body's way of telling you something about your health.