Methylene blue: Should you take it?

Medical uses for methylene blue

Methylene blue is approved by the Food and Drug Administration (FDA) to treat a blood disorder called methemoglobinemia. It has also been used off-label in anesthesia, gastroenterology, pathology, histology and pain medicine. It has been used:

• As part of the treatment for cyanide poisoning
• To dye tissues during surgery to determine tumors
• To relieve pain caused by oral mucositis
• To identify orthopedic injury to joint capsules
• To treat malaria before modern treatments were developed
• To treat encephalopathy, or confusion caused by chemotherapy

Exploring other uses for methylene blue

Earlier in my career, while working in emergency medicine, I read two papers that discussed using methylene blue as part of photodynamic therapy for lichen planus, a type of precancerous lesion in the mouth. Both papers noted that this approach helped reduce patients’ pain. That caught my attention.

In emergency medicine, you’re exposed to a lot of situations where you don’t have many options and need to find a solution. One such scenario I was in involved an emergency room patient in excruciating pain. Nothing was helping. I remembered what I’d read about methylene blue. The patient didn’t have any contraindications, or reasons we’d advise against using methylene blue. So, even though it had never been done before, we tried it. It worked: the patient’s pain was relieved.

After coming to UT MD Anderson, I began working with patients whose cancer treatment caused oral mucositis, inflammation in the gastrointestinal tract that can cause mouth sores and ulcers. In many cases, nothing helped patients manage this pain. Once again, I remembered methylene blue. I reviewed the literature and determined the dosage that we could apply directly into patients’ sores and ulcers. I determined that, at worst, the methylene blue simply wouldn’t work. Fortunately, it worked very well.

Momentum began to build. I began treating more patients who had oral mucositis with methylene blue. I published several papers on the topic and went on to do a randomized clinical trial using methylene blue to treat oral mucositis pain caused by cancer treatment. Of the 60 patients who completed the study, those who used methylene blue oral rinse reported significantly reduced pain after two days of treatment.

Today, methylene blue has been used for mucositis in at least 11 countries.

What to know about methylene blue health claims

In addition to physicians like me, people outside of the medical field also have been intrigued by methylene blue and its potential uses. Search online, and you’ll see methylene blue being sold for many purposes — including as a fish tank cleaner. It’s inexpensive, and it isn’t a controlled substance. This makes it possible for people to buy their own and try it for any number of conditi,ons ranging from hair growth to ADHD treatment.

It can be hard to tell which methylene blue claims are research-backed and which aren’t. But, like I tell my kids, not everything you read online is true. Plus, when you buy products online, there are risks. That's why it’s so important to work with a health care provider who is familiar with methylene blue.

Methylene blue isn’t safe for everyone

Methylene blue isn’t the right choice for everybody. A doctor or health care provider can assess whether it is safe for you to use methylene blue and in what dose and tell you what to avoid while using it.

For example, you should avoid methylene blue if you are:

• Allergic to dyes
• Pregnant
• Taking medications rich in serotonin, including some analgesics and antidepressants. Methylene blue is a monoamine oxidase inhibitor, a substance that has an antidepressant effect. Taking methylene blue in combination with these medications can put you at risk for a potentially deadly condition called serotonin syndrome, which can cause high fever, high blood pressure, seizures and confusion.

What to avoid while taking methylene blue

If you consume methylene blue, avoid food and drinks rich in tyramine. This includes:

• Red wine
• Draft beer
• Aged and fermented cheeses and meats
• Preserved foods

Because methylene blue is a monoamine oxidase inhibitor, combining methylene blue and foods and drinks rich in tyramine can cause a reaction such as uncontrolled hypertension, which puts you at risk of a stroke or heart attack.

Another note? While doctors may inject methylene blue during certain procedures, this isn’t something you should do yourself. This is because injecting methylene blue near nerves can kill them.

Oral methylene blue side effects

One promising aspect of using methylene blue for pain management? Unlike other pain medications, such as narcotics, it doesn’t cause side effects like constipation. But if swallowed, methylene blue can turn your urine and stool green until it’s out of your system; this is normal and nothing to worry about.

Another rare side effect? In my studies of patients using methylene blue oral rinse, about 5% of patients reported a burning sensation the first time they used the solution. In most cases, the burning went away by the second or third use.

When I’ve looked at literature on methylene blue, I’ve only found one case report of toxicity in humans; it resolved quickly and without medical intervention. However, that doesn’t mean that too much methylene blue can’t make you sick. That’s why it’s important to work with a health care provider who can help you determine an appropriate dose.

While not a side effect per se, I also warn my patients that methylene blue can stain. This made it a good clothing dye, but it also means if you get it on linen, carpets or clothes, it's not going to come out — my newly blue lab coats can attest to this!

What’s next for methylene blue research

My current focus is on finding ways to use methylene blue for pain management. I’ve found that applying methylene blue directly to a spot works like a charm. It’s very exciting because I've been able to help a lot of people.

Methylene blue is low-tech, low-cost, accessible and available everywhere. There are uses to be explored, and, potentially, properties we have yet to discover. I'm excited because I know that methylene blue can help millions of people around the globe.

While you can buy methylene blue online, I recommend working with a provider who is familiar with its use and can make sure it’s the best choice for you.

Carlos Roldan, M.D., is a pain medicine physician at UT MD Anderson.

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