When it comes to tampons, the rule of thumb is to never leave them in longer than 8 hours.

According to the Food and Drug Administration (FDA), it’s best to change a tampon after 4 to 8 hours.

To be on the safe side, most experts recommend 4 to 6 hours.

It might sound like an arbitrary time limit, but this amount of time ensures that you won’t put yourself at risk for infection.

Well, that really depends. If you sleep 6 to 8 hours a night, then you’re generally fine to wear a tampon to bed.

Just remember to insert it right before you go to sleep and remove it or change it as soon as you wake up.

If you sleep longer than 8 hours a night, you might want to explore other hygiene products.

Some people prefer to use pads at night and tampons during the day, while others prefer to free flow while sleeping in lined underwear.

Swimming or sitting in water with a tampon is totally fine. You might find that the tampon will absorb a small amount of water, but that’s normal.

In this case, change your tampon after you’re done for the day or the next time you take a break.

If you’re worried about the tampon string poking out of swimwear, you can tuck it inside your labia.

While it’s safe to wear a tampon in water, the same isn’t true for pads. If you’re seeking an alternative option to tampons for swimming or wading in water, consider trying menstrual cups.

After 8 hours of wearing a tampon, your risk of experiencing irritation or developing an infection increases.

The longer that a tampon sits in the body, the more likely it becomes for bacteria to produce toxins that can enter the bloodstream through the uterus or vaginal lining.

When this happens, it can cause a rare, life threatening bacterial illness called toxic shock syndrome (TSS).

TSS symptoms include:

  • a sudden high fever
  • low blood pressure
  • nausea
  • vomiting
  • diarrhea
  • sunburn-like rash

Yes. The National Organization for Rare Disorders estimates that toxic shock syndrome caused by tampons occurs in around 1 in 100,000 menstruating people each year.

It’s important to note that reported tampon-related cases of TSS have significantly decreased in recent years.

Many estimate that this is due in large part to the Centers for Disease Control and Prevention’s standardized absorbency labeling of tampons.

This very rare illness is associated with life threatening and more extreme problems, such as:

Although TSS is extremely rare, this doesn’t mean you should put your body at risk. There are still other infections or irritations that can occur when you leave a tampon in for longer than 8 hours.

Vaginitis

This is an umbrella term for a variety of disorders that cause infection or inflammation. These types of infections are caused by bacteria, yeast, or viruses and are much more common than TSS.

Be on the lookout for symptoms like abnormal discharge, itching, or burning — all of which can be aggravated by sexual intercourse.

If you experience any of these symptoms, talk to a doctor or other healthcare provider.

Most symptoms will go away on their own or with over-the-counter medication. However it’s important to follow your provider’s directions.

Bacterial vaginosis (BV)

This type of vaginitis is one of the most widespread. It’s caused by changes of bacteria in the vagina.

While it’s common to get BV from sexual intercourse, it’s not classified as an STI, and it’s not the only way to get BV.

Keep an eye out for symptoms like unusual or smelly discharge, burning, itching, or general vaginal irritation. If you notice any of these symptoms, talk to a healthcare provider. They’ll likely prescribe antibiotics.

Genital contact allergy

For some people, tampon use can result in an allergic reaction. With prolonged use, this allergic reaction can cause symptoms like itching, soreness, or rashes.

If this occurs, see a healthcare provider. They’ll be able to suggest alternative hygiene products, such as organic cotton tampons, menstrual cups, or lined underwear.

If you experience any of the symptoms above, it might be a tip-off that something unusual is going on. See a doctor or other healthcare provider as soon as you notice anything abnormal.

Early diagnosis is essential in treating TSS.

For more mild conditions, you can expect treatment with intravenous (IV) fluids or IV antibiotics. More serious cases might need additional care to prevent serious organ damage.

To err on the side of caution, remove a tampon after 4 to 6 hours, but no longer than 8 hours.

After 8 hours, your risk of developing TSS — along with other infections or irritations — increases. Although TSS is very rare, it’s always best to be careful when it comes to your menstrual health.

If you find it difficult to remember removing your tampon every 4 to 6 hours, set an alarm reminder on your phone or explore other hygiene options, such as pads, menstrual cups, or lined underwear.

Jen Anderson is a wellness contributor at Healthline. She writes and edits for various lifestyle and beauty publications, with bylines at Refinery29, Byrdie, MyDomaine, and bareMinerals. When not typing away, you can find Jen practicing yoga, diffusing essential oils, watching Food Network, or guzzling a cup of coffee. You can follow her NYC adventures on Twitter and Instagram.