Common Questions About Juice Cleanses

Juice Fasts
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1. How do people typically feel on a cleanse?

Some people feel mild discomfort in the form of hunger pangs, tiredness or headaches, especially in the first few days of a cleanse. Headaches, sleepiness, or difficulty concentrating may result from caffeine withdrawal if caffeine intake hasn't been gradually reduced prior to starting the cleanse. Following the guidelines to prepare for a detox can help to minimize these symptoms.

Other detox symptoms may include body odor, bad breath, a coated tongue, constipation, loose stools or diarrhea, gas, runny nose or nasal congestion, and acne. If you experience discomfort or other symptoms or complications, it's important to discontinue the cleanse and consult your medical provider. Cleanses shouldn't be uncomfortable. 

If continued for a prolonged time, fasting can lead to nutrient deficiencies, such as protein and calcium deficiencies.

2. Who shouldn’t try a juice cleanse?

People with medical conditions (such as diabetes or liver, kidney, or gallbladder conditions) and those taking medications should consult their medical doctor before trying a juice cleanse. Pregnant or nursing women or children shouldn’t try a juice cleanse.

People shouldn’t go on a juice fast before or after surgery or if they are taking anticoagulant or antiplatelet medication. Juice cleanses or fasts can reduce the level of blood proteins and alter the way prescription drugs are metabolized in the body.

People taking prescription medications should consult their doctors before trying a juice cleanse, and should never discontinue or reduce their medications on their own.

3. What are some of the side effects?

Side effects may include fainting, low blood pressure, headache, abdominal pain, dehydration, low potassium, heart arrhythmias, weight loss, vomiting, appendicitis, and kidney pain, stones and other problems.

Do not attempt a juice fast for longer than three days without supervision by a qualified professional, and if any unusual symptoms occur, discontinue the fast and seek prompt medical attention.

Be aware that eating beets or drinking beet juice can result in red discoloration of stools the same or next day, however, there are other causes of red stools. If in doubt, consult your doctor.

4. I've heard about kale, spinach, and other vegetables being not good for the thyroid or kidneys...

A high intake of certain types of vegetables and fruit may not be appropriate for some. For example, raw cruciferous vegetables (such as cabbage, broccoli, kale, watercress, radishes, and collard greens) contain glucosinolates that may inhibit iodine intake and interfere with thyroid function.

Another example is oxalic acid, found naturally in spinach, swiss chard, watercress, parsley, beets, nuts, and some fruits such as berries. Certain people, such as those with kidney disorders (such as chronic kidney disease, kidney stones), gout, rheumatoid arthritis, and certain types of vulvodynia should avoid heavy or regular consumption of oxalate-rich juices. 

5. How long does a juice cleanse typically last?

A juice fast typically lasts for one to five days.


6. How can I prevent constipation?

It's important to have regular bowel movements while on a juice fast, because toxins are mobilized from the tissues and they must be eliminated from the body through stools (and urine and sweat) or they may be reabsorbed in the body.

Remedies that alternative health practitioners sometimes suggest for constipation include the herb cascara sagrada, the Ayurvedic herb triphala, or magnesium. 

7. How long can juice be stored after it is juiced?

If it's stored tightly covered in the fridge, juice can be stored for 12-24 hours after juicing. If you are bringing it to work, pack it in a thermal container or in a container with an ice pack and place it in the fridge if you can.

8. Can I exercise?

Although cardiovascular exercise boosts the circulation of blood and lymphatic fluid, people should avoid moderate to strenuous exercise during a juice fast. Walking is often recommended. Listen to your body, and stop if you feel lightheaded or weak during a workout.

9. What should I do if I have to attend a work-related or personal event?

If you have to attend an event, try to stick to vegetables, such as salads and crudités. According to proponents, one or two additional meals during a juice cleanse won't ruin it.

10. What do people eat after a juice cleanse?

There should be a gradual return to solid foods. Read the sample guidelines on how to break a cleanse.

Before Trying a Juice Cleanse

If you're considering trying a juice fast, talk with your doctor first. It is not appropriate or safe for everyone, despite widespread availability and use of commercial and home juice fasts.  Also be aware that supplements, including those promoted for cleansing or detoxifying, haven't been tested for safety (you can get additional tips on using supplements here). Self-treating or avoiding or delaying standard care may have serious consequences.


Getting JE1, Gregoire JR, Phul A, Kasten MJ. Oxalate nephropathy due to 'juicing': case report and review. Am J Med. 2013 Sep;126(9):768-72. doi: 10.1016/j.amjmed.2013.03.019. Epub 2013 Jul 3.

Disclaimer: The information contained on this site is intended for educational purposes only and is not a substitute for advice, diagnosis or treatment by a licensed physician. It is not meant to cover all possible precautions, drug interactions, circumstances or adverse effects. You should seek prompt medical care for any health issues and consult your doctor before using alternative medicine or making a change to your regimen.

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