Updated: October 2026
In short: During a Juice Cleanse, hunger, tiredness, headaches and a queasy feeling are common in the first one to three days and usually temporary. Healthline names hunger and weakness as typical companions of fasting methods. Stop and seek medical advice if you feel dizzy, get a racing heart, or if symptoms are severe or persist.
Almost everyone wonders before their first Juice Cleanse: how bad will it be? The honest answer: mostly very doable, but not entirely without side effects. Here are the most common complaints, what helps and where the line for stopping lies.
Which side effects are normal during a Juice Cleanse?
Hunger, flagging energy and headaches are the most common complaints in the first few days. Healthline names hunger and temporary weakness as typical, and thinking can also feel less clear at first. Many people report it gets easier from day 3.
| Complaint | Common cause | What often helps |
|---|---|---|
| Hunger | habit, stomach adjusting | drink water or tea, move briefly, spread servings through the day |
| Tiredness | less energy than usual | rest, early bedtime, a walk |
| Headaches | caffeine withdrawal, drinking too little | cut back on coffee beforehand, enough water |
| Feeling cold | lower energy turnover | hot water bottle, warm tea, warm socks |
| Dizziness | low blood pressure, too little fluid | sit down, drink, get it checked if it persists |
| Digestion | changed amount of fibre | drink plenty, gentle exercise |
The causes are typical explanations, not a diagnosis. If you're unsure whether something is normal, ask.
Why do you get headaches during a Juice Cleanse?
Often because you suddenly get less coffee or sugar and because your fluid balance changes. If you used to drink a lot of coffee, you usually feel it more. The best prevention is to cut back on coffee gradually during the preparation days.
Also drink water and tea throughout the day; the Verbraucherzentrale names at least 2.5 litres of calorie-free drinks for fasting cleanses. A short walk in the fresh air helps many people. If the headaches stay strong, that is a reason to stop.
How do you avoid circulation problems?
With preparation, drinking enough and calm movements. Stand up slowly, avoid hot showers and intense exertion and plan a source of warmth. People with low blood pressure should talk to their doctor beforehand.
A Juice Cleanse at 650 to 845 kcal per day, as with the frank. Juice Cleanses depending on the level, is much milder than therapeutic fasting at 150 to 300 kcal. That lowers the likelihood of strong symptoms but doesn't rule them out.
When should you stop the Juice Cleanse?
With dizziness that doesn't go away, a racing heart, a feeling of fainting, severe nausea, persistent vomiting, severe headaches or unusual pain. Then stop the cleanse, eat something light and seek medical advice.
- Persistent dizziness or near-fainting
- Racing or fluttering heart
- severe nausea or vomiting
- severe, persistent headaches
- Panic, marked restlessness or low mood
What can you do if you sleep badly at night?
Some people sleep more restlessly during a Juice Cleanse because hunger or an empty stomach keeps them awake or because their mind races. Helpful are a calm evening without screens, warm herbal tea, a hot water bottle and fixed bedtimes. Don't leave the last serving too late.
Avoid caffeinated drinks in the afternoon. You'll fall asleep more easily anyway if you've had enough exercise in the fresh air, so plan a walk during the day.
What happens to digestion after the Juice Cleanse?
Many people experience changed digestion in the first days after the cleanse. After fasting, portions and composition are different from before, and the gut has to get used to solid food again. So take it slowly: soup, steamed vegetables, potatoes and oats are good starters. Too much fatty food, alcohol or coffee often leads to discomfort.
If you deal with digestive problems for longer, talk to a doctor. The article Stimulating Digestion collects practical tips.
What's the bottom line?
Side effects of a Juice Cleanse are mostly mild and temporary, but they are real. If you prepare well, drink enough, cut back on coffee beforehand and take the cleanse calmly, you'll generally find it very doable. The most important thing is to watch for warning signs and, if in doubt, to stop the cleanse. That's not a defeat but common sense.
Think about the time afterwards too: with gentle refeeding days, you avoid the second wave of complaints that arises when the gut is confronted with heavy food too quickly.
Who shouldn't do a Juice Cleanse?
Pregnant and breastfeeding women, children and teenagers, people with eating disorders, who are underweight or who have serious illnesses should not fast. With diabetes, gout, high blood pressure or regular medication, you need medical advice beforehand. Our article When a Juice Cleanse Isn't Right explains this in detail.
How do you prevent side effects?
With 2 to 3 preparation days beforehand, plenty of drinking, little time pressure and a fixed plan. The Verbraucherzentrale generally recommends planning 2 to 3 refeeding days after fasting too. You'll find details in our articles Juice Cleanse Preparation and Breaking a Fast.
And don't treat it as a competition. If you cut the cleanse short after a day, you haven't done anything wrong; you listened to your body. Next time you can try again with a milder level or more preparation.
Matching picks from frank.
If you want to start with a mild option, take a look at the 3-Day Juice Cleanse in the Starter level: 845 kcal per day, a fixed drinking plan and a guide.
You might also like
- When a Juice Cleanse Isn't Right
- Juice Cleanse Preparation: Checklist and Schedule for Your Juice Cleanse
- Juice Cleanse Side Effects: Headaches, Feeling Cold and What Helps
Frequently asked questions about Juice Cleanse side effects
How long do side effects last during a Juice Cleanse?
Usually the first one to three days. After that, many people report that it gets easier. If strong symptoms persist, stop the cleanse.
Are headaches normal during a Juice Cleanse?
Headaches are common, especially for coffee drinkers. Cut back on coffee beforehand and drink plenty of water and tea.
Can I exercise during a Juice Cleanse?
Walks and gentle stretching are fine. Put off intense training until later.
What should I do about cravings during a Juice Cleanse?
Drink a glass of water or warm tea, wait ten minutes and move briefly. The impulse often passes.
Can a Juice Cleanse be dangerous?
For healthy adults, a short Juice Cleanse is usually very doable. If you have pre-existing conditions or take medication, talk to your doctor beforehand.
Can I take medication during a Juice Cleanse?
Talk to your doctor beforehand. Some medications must be taken with meals or work differently with less food. Never stop prescription medication on your own.
Note: This article is for general information and is not a substitute for medical or therapeutic advice. If you have complaints, pre-existing conditions, are pregnant or take medication, please talk to your doctor first.
