can intermittent fasting cause dry mouth

Can Intermittent Fasting Cause Dry Mouth?

Written by Andrew Brewer. ⚕️Reviewed and fact checked by our medical team.

can intermittent fasting cause dry mouth

People experienced with keto diets know all about the dry mouth that comes with ketosis, but it might surprise you if you’re doing intermittent fasting.

Ketosis isn’t the only reason for dry mouth during intermittent fasting. It’s even more likely that your mouth is dry because you’re dehydrated.

Intermittent fasting can have many side effects, and dry mouth is one of the first symptoms you will experience.

Key Takeaways

  • Intermittent fasting can cause dry mouth, which is usually due to dehydration caused by natriuresis, the process by which water and salts are released and expelled through urine during fasting.
  • Staying hydrated by drinking water, black coffee, unsweetened black tea, sparkling water, mineral water, and herbal tea is important during fasting to avoid discomfort in the kidneys and other side effects.
  • Keeping your mouth moist by sipping on water, rinsing your mouth with water, and brushing your teeth regularly can help prevent bad breath and maintain good oral health during fasting.
  • The first signs of ketosis during fasting include dry mouth, bad breath, thirst, headaches, flu-like symptoms, suppressed appetite, increased focus and energy, and muscle cramps or spasms.
  • It’s important to take it slow, monitor your water intake, and consult with a doctor before starting intermittent fasting, especially if you have pre-existing conditions like diabetes or if you’re pregnant or nursing.

Stay Hydrated During Intermittent Fasting

During intermittent fasting, it’s common to experience a dry mouth. As your body starts to burn fat, water and salts are released and expelled through your urine. This process is known as natriuresis.

In addition to your dry mouth, fasting-induced natriuresis can cause discomfort in your kidneys. It’s essential to stay hydrated and replace lost electrolytes.

Monitor Your Water Intake

Be sure to monitor your water intake and drink water throughout the day. You should also pay attention to the color of your urine. If it gets too dark, you’re not drinking enough water.

Other Beverages You Can Drink

Water isn’t your only choice when fasting, but you must completely avoid sugars and carbohydrates, so you don’t break your fast.

The best intermittent fasting drinks are black coffee and unsweetened black tea. You can also drink sparkling water, mineral water, and herbal tea, as long as you don’t add honey, cream, or sugar. Many health professionals recommend avoiding artificial sweeteners, too.

Keep Your Mouth Moist While Fasting

Sipping on water is the most recommended way to keep your mouth moist during fasting. You can also rinse your mouth with water without swallowing to keep it moist.

When you stop eating, your body doesn’t produce saliva. Saliva helps keep your mouth naturally clean and rinsed.

Dehydration is a common cause of bad breath, too. Keeping your mouth moist while you’re fasting will help curb this problem.

If bad breath is a problem for you during fasting, try to avoid foods that cause bad breath, like onions and garlic.

Brushing your teeth when your mouth is dry is another way to practice good oral health and combat dry mouth. Toothpaste won’t break your fast as long as you don’t swallow it.

The First Signs of Ketosis

It can take 2-4 days before your body fully enters ketosis. Still, your body will start burning fat after only 12 hours of intermittent fasting apps. It’s even more common to have symptoms of ketosis after 16 hours, especially if you are exercising.

If you’re wondering what’s happening to your body, you are likely experiencing ketosis. Here are some of the first signs of ketosis to watch out for:

  • Dry mouth
  • Bad breath
  • Thirst
  • Headaches
  • Flu-like symptoms
  • Suppressed appetite
  • Increased focus and energy
  • Muscle cramps or spasms

You can get a home testing kit for ketones to test for increased ketones in your bloodstream. It’s a fast and accurate way to tell if your body has entered ketosis.

Side Effects of Intermittent Fasting

The side effects of intermittent fasting are uncomfortable for many people. Sometimes, they are unexpected, but your body will adjust as you continue to fast.

Take it slow when you are first starting, and don’t overdo it. Fasting can have some adverse side effects if you take it too far.

You should avoid intermittent fasting if you are pregnant or nursing, are under 18, are prone to eating disorders, or have pre-existing conditions, such as diabetes. Consult with your doctor before you start intermittent fasting.

If you’re new to intermittent fasting, try a fasting app to help you on your fasting journey. It can make your fasting journey more manageable and successful.


  • Can intermittent fasting cause dry mouth?

Yes, intermittent fasting can cause dry mouth, especially during fasting. This is because fasting reduces saliva production, which can lead to a dry, sticky feeling in the mouth.

  • Why does fasting cause dry mouth?

Fasting causes dry mouth because it reduces the production of saliva. Saliva is essential for lubricating the mouth and preventing dryness. When the body is in a fasted state, it reduces saliva production to conserve energy.

  • What are the other symptoms of dry mouth?

Dry mouth can cause a range of symptoms, including a dry, sticky feeling in the mouth, bad breath, difficulty swallowing, cracked lips, and a sore throat.

  • How can I relieve dry mouth during intermittent fasting?

You can relieve dry mouth during intermittent fasting by drinking plenty of water, chewing sugar-free gum, using a saliva substitute, and avoiding foods and drinks that can cause dryness, such as caffeine, alcohol, and tobacco.

  • Is dry mouth during intermittent fasting a cause for concern?

In most cases, dry mouth during intermittent fasting is not a cause for concern. However, if you experience severe or persistent dry mouth, consult a healthcare professional to rule out any underlying medical conditions.

  • Can intermittent fasting lead to dehydration?

Intermittent fasting can lead to dehydration if you do not drink enough fluids during the fasting period. Drinking plenty of water and other fluids is important to stay hydrated during intermittent fasting.

  • Can dry mouth be a sign of a more serious health condition?

Dry mouth can indicate a more serious health condition, such as diabetes, Sjogren’s syndrome, or Parkinson’s disease. If you experience persistent dry mouth, consult a healthcare professional to rule out any underlying medical conditions.

Andrew Brewer

Andrew Brewer

Andrew Brewer started to give people the guidance that he never received when he was first starting. His goal is to make your goals achievable and to offer you only the best fasting apps that the internet has to offer. You're not on your own - Andrew and the entire family of reviewers at are here with you every step of the way!