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Safety of an ingredient?

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  • Safety of an ingredient?

    I am trying to figure out if taking orally 10 mg of methylene blue is harmful for breastfeeding a toddler? A lot of the information I’m finding online is about methylene blue given by IV.

  • #2

    I would recommend waiting at least 24 hours after taking any methylene blue to breastfeed. When you take it orally, there is a fair amount of absorption which would make the information we have about IV administration useful for oral administration as well. We expect there to be at least some transfer into breastmilk and Dr. Hale classifies it as L4, Possibly Hazardous.

    Keep in mind that methylene blue has many drug interactions with common over the counter drugs such as some cough syrup. Please be cautious (for you or a breastfeeding child) not to use both simultaneously.

    Kaytlin Krutsch, PharmD


    • #3
      OK, I will follow your advice. Do you know why it is classified as possibly hazardous L4 and is it because of the risk of certain things occurring with the blood like methemoglobinemia & hemolysis? Are these things not a risk if the toddler doesn’t have a G6PD deficiency? Thank you.


      • #4

        This is what little we know about its complications.

        Tom Hale Ph.d.

        Cardiac dysrhythmias and hypertension. Sweating, discoloration of skin, malignant hyperthermia, nausea, vomiting, diarrhea. At high doses or in patients with G6PD-deficiency and infants, methylene blue may catalyze the oxidation of ferrous iron in hemoglobin to ferric iron, causing paradoxical methemoglobinemia and hemolysis. Onset of anemia may be delayed 10 or more days and may require red blood cell transfusions.


        • #5
          OK, I wasn’t sure if I’m breastfeeding a toddler, not an infant & if I believe him to not have a G6PD deficiency, if the risk of methemoglobinemia and hemolysis is still high. I also wasn’t sure if 10 mg methylene blue orally is a high dose. Thank you for writing.


          • #6

            The IV dose is : 1 mg/kg over 5 to 30 minutes, may repeat dose 1 hour later if methemoglobin level remains above 30% or symptoms persist; consider alternative therapy if resolution does not occur after 2 doses

            There is no ORAL dose published that I know of.

            While the risk is evident, I don't know the probability it will occur. Its rather unlikely, but its up to you if you want to expose your infant.

            Tom Hale Ph.D.


            • #7
              I understand. It sounds iffy and will err on the side of caution although I want to just reiterate my little one is a toddler (about 2.75), not an infant. Does still nurse quite a bit. I did find one source that said they didn’t expect methylene blue to cause adverse effects in a nursing infant here, all the way at the bottom under Breasfeeding Summary but I didn’t know if this was a reliable source: [url][/url]

              Also, one last thing, I wanted to check something on phenazopyridine. Everything I checked in the forums and on the MommyMeds app made it sound safe enough for breastfeeding although you find it to be only minimally effective, but I found info on lactmed that conflicts: The safety of phenazopyridine is not established in infants or during breastfeeding. Because it can cause methemoglobinemia, sulfhemoglobinemia, and hemolytic anemia, it should be avoided while breastfeeding, especially with an infant under 1 month of age or with glucose-6-phosphate dehydrogenase (G6PD) deficiency.[url][/url]

              Just trying to clarify because want to make the safest choice for my issue.
              Last edited by stratton1019; 10-26-2020, 07:41 PM. Reason: Wanted to add info


              • #8

                Although I have never heard of the first website, the information it has comes from a reputable textbook.

                Phenazopyridine does have rare case reports of the adverse effects you mentioned. We think it has rapid excretion which helps with the safety profile for an infant. It is hard to say on these old drugs that do not have pharmacokinetic profiles for us to evaluate. We must be cautious when a patient is taking multiple drugs with the same risks--we don't know how they will affect each other.

                From what we know about your situation, it is likely that the risks of breastfeeding outweigh the benefits while on these medications. But, as Dr. Hale mentioned, it is up to you.



                • #9
                  Ok, thank you for your reply and all your help. Just to clarify, I wouldn’t be taking both the phenazopyridine and the methylene blue (the medication that has that in it that I’m researching is called Uribel), it would be one or the other. I will make an informed decision about whether take the phenazopyridine or the Uribel (the one with methylene blue). Do you know when these adverse effects could show up if I did take either medication? Would it be right away or could It happen after a while of use? And from a pharmacological standpoint do both phenazopyridine & methylene blue work similarly? Like, if one medicine was tried like the phenazopyridine didn’t cause any adverse side effects like with the hemolysis or methemoglobinemia would it be logical to infer that the methylene blue wouldn’t either?
                  Last edited by stratton1019; 10-26-2020, 10:00 PM. Reason: Added a question at the end