Methylene Blue and Fasting: Does It Break a Fast? 2026

By NooBlue Editorial · About our editorial standards

Short answer: no, methylene blue does not break a fast. The compound supplies no usable energy and no protein. What can break a strict fast is what comes with it, such as a gummy base, a sweetener or the juice you mix drops into. Drops in plain water are the only format that fits a zero-calorie window.

People ask about methylene blue and fasting because both get talked about as ways to support cellular energy, and many people who fast want something for focus during the hours they are not eating. This guide covers what counts as breaking a fast, how each methylene blue format fits a fasting window, what the research does and does not show, how to time a dose, and who should not take it at all. NooBlue makes methylene blue capsules, gummies and drops, so we will also say plainly which of ours suits a fast and which is better kept for your eating window.

Does Methylene Blue Break a Fast?

A fast ends when you take in enough energy or protein to move your body out of the fasted state. What counts depends on why you fast. A strict water fast allows nothing but water. Time-restricted eating is usually about calories and insulin. People who fast for autophagy also watch protein, because amino acids switch on mTOR, the growth signal that turns autophagy down.

Methylene blue passes all three tests. A daily supplement dose is measured in single milligrams, and the molecule is not a carbohydrate, fat or protein. It gives your body nothing to burn and nothing to build with, so on the metabolic definition of a fast it stays in the clear.

The format is a different matter. Gummies need a base and a sweetener. Some capsules are meant to be taken with a meal. Drops are only as clean as the drink you mix them into. So the useful question is not “does methylene blue break a fast?” but “does this product, taken this way, break my fast?” Our guide to how many mg of methylene blue per day covers the dose side of that question.

How each NooBlue format fits a fasting window

Whether 6 calories matters depends on your rules. If your fast is zero calories, take the gummy when you eat. If you fast mainly to shorten your eating window, you can decide whether a 6-calorie chew with no sugar fits. Either way, the gummies do not leave the blue mouth and tongue that drops can.

Methylene Blue and Fasting, Goal by Goal

Here is how pure methylene blue lines up against the common reasons people fast. “Pure” means the compound itself, before any gummy base or drink is added.

Why People Pair Methylene Blue With Fasting

When you stop eating, the glycogen stored in your liver runs down and your body leans more on fat and ketones for fuel. Both are burned inside the mitochondria, where the electron transport chain turns fuel into ATP, the cell’s energy currency. That shared location is the whole reason the two get discussed together.

Electron cycling. At low doses, methylene blue shuttles electrons inside the mitochondria. Cell enzymes hand it electrons, which turns it into its colorless form, leucomethylene blue, and cytochrome c takes those electrons back. In cultured human cells this raised the activity of mitochondrial complex IV by 30% and cell oxygen consumption by 37 to 70% (Atamna and colleagues, FASEB Journal, 2008). A review from Francisco Gonzalez-Lima’s group at the University of Texas describes the same low-dose electron cycling and notes that methylene blue has a hormetic dose response, with opposite effects at low and high doses (Rojas and colleagues, Progress in Neurobiology, 2012). That is one of the clearest reasons to keep the dose low.

Energy sensors. Fasting is a low-energy state, and cells track it with sensors such as AMPK and SIRT1. In liver cells and mice, methylene blue raised the NAD+/NADH ratio, switched on SIRT1 and, through it, AMPK (Shin and colleagues, European Journal of Pharmacology, 2014). The authors describe SIRT1 activation as mimicking calorie restriction. That was a liver-fat study in mice fed a high-fat diet, though, not a fasting study in people.

Autophagy. Autophagy is the cell’s recycling system, and fasting is one of the things that encourages it. Two lab studies found methylene blue switched it on. In mouse nerve cells starved of serum, methylene blue induced autophagy through AMPK, and the same happened in the brains of mice given methylene blue (Xie and colleagues, Frontiers in Cellular Neuroscience, 2013). A Columbia University team found it acted as an autophagy inducer in cell and mouse models, with a mode of action similar to rapamycin (Congdon and colleagues, Autophagy, 2012).

The human studies. Human research on methylene blue has looked at the brain rather than at fasting. In a randomized, double-blind, placebo-controlled trial with 26 adults, a single low oral dose increased brain activity during attention and short-term memory tasks and was linked to a 7% increase in correct memory-retrieval responses an hour later (Rodriguez and colleagues, Radiology, 2016). A related analysis from the same team found stronger connectivity between brain networks tied to perception and memory (Rodriguez and colleagues, Brain Imaging and Behavior, 2017). Our overview of what the research shows about methylene blue benefits covers the rest, and our guide to methylene blue for energy covers the day-to-day side.

What the Research Does Not Show

The overlap above is real biology, but it has limits worth stating plainly.

• No fasting trial. No human study has given methylene blue during a fast and measured ketones, blood sugar, autophagy, hunger or weight.
• Lab findings are not outcomes. The AMPK and autophagy results come from cells and mice under controlled conditions. They are a reason for interest, not proof that 5 or 10 mg a day changes anything in a fasting person.
• No appetite effect shown. Some fasting content says methylene blue blunts hunger. We found no controlled human trial showing that. Our reality check on methylene blue and appetite goes through the evidence.
• Not a fat-loss product. No human trial shows that adding methylene blue to a fast increases fat loss, and NooBlue does not sell it for weight loss. Our answer to does methylene blue help with weight loss has the detail.

The fair summary is that methylene blue fits inside a fast without breaking it, and some people like it for steady focus during the hours they are not eating. The fast still does the metabolic work.

How to Take Methylene Blue While Fasting

1. Match the format to your window. Drops go into plain water at any point in a fast. Take the capsule with your first meal, as its label says. If your fast is zero calories, keep the gummy for your eating window.
2. Stay at the label serving. Ten drops of a 1% solution is 5 mg. Our capsule is 5 mg, one a day, and our gummy is 10 mg, one a day. Do not exceed the suggested serving. Fasting is not a reason to take more.
3. Use water, not juice. The drops label says water or juice, but juice brings sugar with it. In a fasting window, use plain water.
4. Take it earlier in the day. Most people take methylene blue in the morning so any lift in focus lands during working hours. Our guide to the best time to take methylene blue explains why an afternoon cutoff helps protect sleep.
5. Think about the coffee. Many people get through a fast on black coffee. Our guide to combining methylene blue and caffeine covers how the two sit together and when to space them.
6. Training fasted? See our notes on taking methylene blue before a workout.
7. Listen to your stomach. If a dose on an empty stomach does not sit well, move it to your first meal. Nausea is one of the side effects reported with methylene blue in medical use, where doses are much higher.
8. Expect colored urine. Urine can turn blue or green with any format. That is expected, and our page on methylene blue urine color explains how long it lasts. Drops can also stain the mouth and tongue, which the gummies avoid.

Safety: Who Should Not Take Methylene Blue

The serotonin risk comes from how methylene blue works. It is a potent inhibitor of monoamine oxidase A, the enzyme that breaks down serotonin (Ramsay and colleagues, British Journal of Pharmacology, 2007), and a systematic review of case reports linked it with serotonin syndrome in people taking serotonin reuptake inhibitors (Ng and Cameron, Psychosomatics, 2010). Our guides to methylene blue and serotonin syndrome and what not to take with methylene blue go further.

The G6PD rule exists because methylene blue can break down red blood cells in people who lack that enzyme (Ostrovsky and Afzal, StatPearls, 2026). If you are not sure of your status, our page on methylene blue and G6PD deficiency explains the test. Fasting adds one more reason to speak to your doctor first: if you take medicine that lowers blood sugar or blood pressure, check whether fasting itself is safe for you before adding anything to it.

Which NooBlue Format Suits a Fasting Routine

NooBlue makes all three formats, and for fasting they sort themselves by timing.

• Drops for the fasting window. NooBlue Methylene Blue Drops are a 1% solution of methylene blue USP in distilled water, $29.99 for 50 mL. At 10 drops (5 mg) a serving, a bottle gives about 100 servings, roughly $0.30 each. They are the only format that fits a strict zero-calorie fast. They can stain the mouth, so mix them into water.
• Capsules for the first meal. NooBlue Methylene Blue Capsules hold 5 mg of methylene blue USP and 10 mg of vitamin C, 60 to a bottle, $37.99, about $0.63 a capsule. Nothing to measure and no taste. The label says one a day with food.
• Gummies for the eating window. NooBlue Methylene Blue Gummies carry 10 mg of methylene blue USP and 25 mg of vitamin C, 60 to a bottle, $49.99, about $0.83 a gummy. They have 6 calories and 0 g sugar each and do not leave a blue mouth.

On testing, we publish exactly what we have. Contract Testing Laboratories of America (CTLA) analyzed the methylene blue ingredient lot we use and recorded an HPLC identity result and individual results for arsenic, cadmium, mercury and lead. That is ingredient-level evidence. It does not give a purity percentage or certify every finished batch. Our guide to what methylene blue purity claims mean explains how to read reports like this, including other brands’. If you are still choosing between chewables and liquid, see methylene blue gummies vs liquid, our methylene blue reviews roundup, or browse the full NooBlue range. Orders over $100 ship free worldwide.

Frequently Asked Questions

Does methylene blue break a fast?

No. A supplement dose of methylene blue is a few milligrams of a molecule that is not a carbohydrate, fat or protein, so it gives your body no fuel and does not end the fasted state. What can break a strict fast is the format: a gummy base, a sweetener, or juice used to mix drops. Drops in plain water fit a zero-calorie window.

Do methylene blue gummies break a fast?

Strictly, yes, because they are food. NooBlue gummies have 6 calories and 0 g sugar each, sweetened with stevia. If your fast allows zero calories, take the gummy at the start of your eating window. If your plan tolerates a few calories, it is your call.

Can I take methylene blue on an empty stomach?

Drops mixed into water are commonly taken during a fast. NooBlue capsules are labeled to be taken with food, so people who fast usually take them with their first meal. If any dose on an empty stomach does not sit well, move it to a meal.

Does methylene blue stop autophagy?

There is no sign that it does. It contains no amino acids to switch on mTOR, and in cell and mouse studies methylene blue induced autophagy rather than blocking it. No human study has measured autophagy after methylene blue, so treat any claim that it boosts autophagy in people as unproven.

Does methylene blue affect ketosis?

It is not expected to. Ketosis depends on low insulin and depleted glycogen, and pure methylene blue supplies no carbohydrate to change either. No study has measured ketone levels after methylene blue, fasted or fed.

Can I take methylene blue with black coffee while fasting?

Yes, if you do not take serotonergic medicines and have no other reason to avoid it. Plain black coffee and methylene blue drops in water both fit most fasts. Keep both earlier in the day to protect your sleep, and do not raise the methylene blue dose because you are fasting.

Will methylene blue make fasting easier or increase fat loss?

No human trial shows that methylene blue reduces hunger or increases fat loss during a fast. Some people like it for steady focus while they are not eating, and that may help them stick to their window, but the fast does the metabolic work. NooBlue does not sell methylene blue as a weight-loss product.

Does methylene blue have calories?

The methylene blue itself adds no meaningful calories. It is a dye molecule dosed in milligrams, not a nutrient your body burns for energy. Any calories in a product come from the other ingredients, such as the 6 calories in a NooBlue gummy.

Sources

1. Atamna H, Nguyen A, Schultz C, et al. Methylene blue delays cellular senescence and enhances key mitochondrial biochemical pathways. FASEB Journal. 2008;22(3):703-712. PubMed 17928358
2. Rojas JC, Bruchey AK, Gonzalez-Lima F. Neurometabolic mechanisms for memory enhancement and neuroprotection of methylene blue. Progress in Neurobiology. 2012;96(1):32-45. PubMed 22067440
3. Shin SY, Kim TH, Wu H, Choi YH, Kim SG. SIRT1 activation by methylene blue, a repurposed drug, leads to AMPK-mediated inhibition of steatosis and steatohepatitis. European Journal of Pharmacology. 2014;727:115-124. PubMed 24486702
4. Xie L, Li W, Winters A, et al. Methylene blue induces macroautophagy through 5′ adenosine monophosphate-activated protein kinase pathway to protect neurons from serum deprivation. Frontiers in Cellular Neuroscience. 2013;7:56. PubMed 23653592
5. Congdon EE, Wu JW, Myeku N, et al. Methylthioninium chloride (methylene blue) induces autophagy and attenuates tauopathy in vitro and in vivo. Autophagy. 2012;8(4):609-622. PubMed 22361619
6. Rodriguez P, Zhou W, Barrett DW, et al. Multimodal randomized functional MR imaging of the effects of methylene blue in the human brain. Radiology. 2016;281(2):516-526. PubMed 27351678
7. Rodriguez P, Singh AP, Malloy KE, et al. Methylene blue modulates functional connectivity in the human brain. Brain Imaging and Behavior. 2017;11(3):640-648. PubMed 26961091
8. Ramsay RR, Dunford C, Gillman PK. Methylene blue and serotonin toxicity: inhibition of monoamine oxidase A (MAO A) confirms a theoretical prediction. British Journal of Pharmacology. 2007;152(6):946-951. PubMed 17721552
9. Ng BK, Cameron AJ. The role of methylene blue in serotonin syndrome: a systematic review. Psychosomatics. 2010;51(3):194-200. PubMed 20484716
10. Ostrovsky A, Afzal M. Methylene Blue. StatPearls. Updated January 2026. NCBI Bookshelf NBK557593

This article is for educational purposes only and is not medical advice. Talk to your doctor before starting methylene blue or a fasting plan, especially if you take any prescription medicine.