No announcement yet.

Hyperthyroidism medication(PTU) and breastfeeding

  • Filter
  • Time
  • Show
Clear All
new posts

  • Hyperthyroidism medication(PTU) and breastfeeding

    Hi all,

    My name is Vasudha and I have 4 and half months baby girl. I am just diagnosed for hyperthyroidism (T4 - 20 and TSH - 0.01). Doctor has put me on PTU medicine 100mg two times a day. My doctor does not have a definite answer when I ask him can I breast feed my baby. He says we need to monitor her closely. I am dead scared thinking what if it affects my baby. I have stopped feeding her my milk and giving her formula and she is really really fussy and cranky. She just doesn't like it.

    My supply was quite low before I started taking medication. Since I express and give her milk i know this. I have already started on PTU and my supply all of a sudden increased just after one dosage. My heart pops out when throw the expressed milk in the sink.
    It is very traumatic for my little girl and baby to have formula.

    Is it absolutely safe to breastfeed while on PTU medication for hyperthyroidism ?
    Or is there any other alternative.

    One more thing. I was diagnosed for hypothyroidism when I was just pregnant. My doctor says it was due to pregnancy and I was on 75micrograms of thyroxine supplement throughout pregnancy. After delivery I took 25 micrograms but I did not realize when it became hyper.

    Now my TSH level is 0.01, T4: 20.01, T3:2.8

    Please help. My baby is starving!


  • #2

    We have good data on the transfer of PTU(propylthiouracil) and methimazole into human milk and both are generally considered safe to use in breastfeeding mothers. We've used both of these medications for years without any problem in breastfed infants.

    I'd suggest you restart breastfeeding immediately. If you worry about this drug and breastfeeding, simply have your pediatrician do a T4 level on your infant after a month or so. I'm sure it will be normal.

    If you have further questions, call the InfantRisk Center hotline, 806-352-2519

    Tom Hale Ph.D.


    • #3
      Thanks a lot for the information.

      I am getting her back to breastfeeding from today. I will be on 50mg two times a day. To be safe I am going to express the milk 3 hrs after I take the medicine and discard the same. I will feed her later on.

      I am hoping for the best.



      • #4
        Further query about PTU


        I need more information with respect to hyperthyroid medication and breastfeeding.

        1. Is methimazole better than PTU for breastfeeding? (Currently I am on 50mg ptu , two times a day)

        2. I am not feeding her the milk that I express 3 hours later I take the medicine. I am discarding that milk. I feed her then onwards. Does that decrease the affects of ptu or is it just mere waste of my milk? My supply is quite low already because of my thyroid condition and my little girl has growing demands.
        Or should I just feed her around 4 hours later I take the medicine. Which one is better? Discarding the first expressed milk or just feed her after 4 hours?

        Please let me know.

        Thanks and Regards,
        Last edited by Vasudha; 06-25-2011, 12:48 PM.


        • #5

          1) Technically yes. PTU works just as well, its just it has a few more side effects in patients, and it has to be administered 2-3 times daily. Methimazole is a once-a-day dose...nice.

          2) If you are using PTU or Methimazole, I would not pump and discard at 3 hours. It's a waste of time and good milk. The milk would be better used by your infant.

          Tom Hale Ph.d.


          • #6

            I'm syeril and I have a 8 months of baby girl. I am full breastfeeding her until now. I was diagnosed having hyperthyroid 4 months after delivery as my eczema slowly to cure. Doctor ask me to take Carbimazole and to stop breastfeed. I refused that treatment and continue my breastfeeding.

            Is it true that I have to stop breastfeeding if on Carbimazole.
            I want to breastfeed my baby..but I am still worry of my health and the effect on not treating the hyperthyroid.

            My T3 level is 5.0, T4 10.12 and TSH 0.31

            Please help me.

            Thank you


            • #7
              Dear Syeril

              Carbimazole is a prodrug and is rapidly converted to methimazole. It is used to inhibit the secretion of thyroxine. Carbimazole usage during breastfeeding is probably safe. There are lots of data reporting no untoward effects to the infant for periods up to 12 months. Monitor thyroid function of the breastfed infant to be safe.

              For further questions, please contact the InfantRisk Center at 806-352-2519.

              Tassneem Abdel Karim
              InfantRisk Center


              • #8
                I've been diagnosed with Grave's disease (hyper) and have been given PTU for 100mg 3x a day. My doctor told me that she recommends I stop breastfeeding and put my now 6month old on formula or if I want to breastfeed to wait 3hrs after I take the meds. My baby takes formula/pumped milk but really doesn't care for being away from me that long throughout the day- for a really happy and smiley baby it was shocking to see her stop smiling and being happy. I have stop taking my meds in order to figure something out. Is it really safe to breastfeed while on PTU 300mg or 200mg a day for another 6 months or more?
                Please help, I am in Korea where they take absolutely no risks.


                • #9
                  Hi, thanks for your post.

                  Yes, it really is safe to breastfeed while on 200-300mg of PTU per day. The case studies that support this claim were done in women taking 400mg / day and there were no problems reported in the babies. It is not necessary to wait for 3 hours before feeding or to discard any milk. Have your pediatrician do blood tests of your baby's thyroid about a month after you start taking the PTU, just to make absolutely sure. In the next six months, your baby will begin to eat solid foods and drink less milk relative to her body weight, making the drug even safer. You should be able to take this medication for as long as you need to.

                  You did not ask this, but I have to mention it in case we do not speak again. Radioactive iodine is sometimes used as part of thyroid scans or to destroy part of an overactive thyroid. This medication is extremely dangerous for breastfed infants. PLEASE do not breastfeed if you receive radioactive iodine, especially I-131. We, or some other expert, can help you determine when it is safe to feed again.

                  Please call us at the InfantRisk Center if this has not completely answered your question.*(806)352-2519

                  -James Abbey, MD


                  • #10

                    I was diagnosed with hyperthyreosis. I have a 3 month old baby and I am breastfeeding her exclusively. Dr perscribed me propylthiouracil 3x100 mg, metoprolol 3x25 mg (only when my HR exceedes 100 bpm) and diazepam 3x2 mg. I have already red all your previous posts about PTU and I decided to take it without any fear. I haven't started with other two medications. I guess that I could manage without diazepam, but my HR goes up to 130 bpm and I think that metoprolol would help me with that. Is it safe for my baby if I take metoprolol in full perscribed dose? Is it any safer if I use metoprolol only when needed? How dangerous is diazepam in breastmilk?

                    Thank You!


                    • #11
                      Hi, thanks for your post.

                      Metoprolol is a fairly safe medication to use while breastfeeding. Only 1-2% of what you take makes it to the infant and that is usually too little to have any effect. You should take this drug only when needed. If you take it when your heart rate is normal, it can end up dropping too low. When you do take it, watch your baby for sedation or other changes in behavior.

                      Diazepam causes similar symptoms in the baby, has a long half-life, and more of it transfers into the breastmilk. It is a little riskier than the metoprolol, so try to use that first. The risks decline significantly when your baby is around 9 months old. Try to keep your use of this medication at a minimum until then.

                      Please call us at the InfantRisk Center if this has not completely answered your question.*(806)352-2519

                      -James Abbey, MD


                      • #12
                        Hi guys,
                        My hyperthyroidism has returned since having my baby. The endocrinologist has put me on 3 tablets of carbimazol a day which is 15mg. But i am breastfeeding which he knows, and on the package instructions it says if breastfeeding to have only 10mg daily maximum. What should i do?


                        • #13
                          The drug manufacturers take a very conservative position when it comes to breastfeeding on their products. In the study cited at the bottom, the researcher tested drug levels in infants (twins) breastfeeding from a mother who was taking 30mg/day. The level of medication in the babies was still below the effective level that actually suppresses thyroid function. We recommend that you continue breastfeeding your child while on 15mg/day. If you still have concerns after a couple of weeks, have your baby's thyroid hormone levels tested.

                          -James Abbey, MD


                          • #14
                            Hello everyone,

                            I am a mother to a 9 month old infant who I am currently breastfeeding. I was diagnosed with hyperthyroidism a month and a half ago (cause unknown yet) and was started on PTU (propylthyouracil) initially 100mg/day then increased to 200mg/day due to continued symptoms. I have continued breastfeeding after doing research and noting infants' thyroid function is usually unaffected.

                            However, today I found out at my appointment with my endocrinologist that my liver is being damaged and my WBC is decreased, likely due to the PTU since these are known side effects of this drug. She would like me to lower the dose and check again in two weeks. But I don't feel comfortable taking PTU any longer because of the damage it is causing. I would like to ask her to put me on Methimazole instead and from other posts I have seen here, it seems this is very reasonable, if not preferred. My concern is that she (my endocrinologist) thinks that the other antithyroid medications are not compatible with breastfeeding. What source can I provide my doctor in case she does not want to prescribe the medication to me? Thanks in advance for your help.


                            • #15

                              Methimazole is rated an L2-limited data-probably compatible. The amount transferred into breast milk is 2.3% of your dose. [COLOR=#333333][FONT=lucida grande]Methimazole usage during breastfeeding is probably safe. There are lots of data reporting no untoward effects to the infant for periods up to 12 months. Here are the studies we have along with references that you could present to your Dr.[/FONT][/COLOR]

                              Levels of methimazole in milk depend on the maternal dose but appear too low to produce clinical effects. In one study of a single patient receiving 2.5 mg methimazole every 12 hours, the milk/serum ratio was 1.16, and the dose per day was calculated at 16-39 mcg methimazole.[1] This was equivalent to 7-16% of the maternal dose.

                              In another study of 35 lactating women receiving 5 to 20 mg/day of methimazole, no changes in the infant thyroid function were noted in any infant, even those at higher doses.[2] Further, studies by Lamberg in 11 women, who were treated with the methimazole derivative carbimazole (5-15 mg daily, equal to 3.3 -10 mg methimazole), found all 11 infants had normal thyroid function following maternal treatments.[3] Thus, in small maternal doses, methimazole may also be safe for the nursing mother. In a study of a woman with twins who was receiving up to 30 mg carbimazole daily, the average methimazole concentration in milk was 43 mcg/L.[4] The average plasma concentrations in the twin infants were 45 and 52 ng/mL, which is below therapeutic range. Methimazole milk concentrations peaked at 2-4 hours after a carbimazole dose. No changes in thyroid function in these infants were noted. In a large study of over 134 thyrotoxic lactating mothers and their infants. Methimazole therapy was initiated at 10-30 mg/day for one month, and reduced to 5-10 mg/day subsequently. Even at methimazole doses of 20 mg/day, no changes in infant TSH, T4 or T3 were noted in over 12 months of study.[5] The authors conclude that both PTU and methimazole can safely be administered during lactation. However, during the first few months of therapy, monitoring of infant thyroid functioning is recommended.

                              .##Tegler L, Lindstrom B. Antithyroid drugs in milk. Lancet 1980; 2(8194):591.
                              2.##Azizi F. Effect of methimazole treatment of maternal thyrotoxicosis on thyroid function in breast-feeding infants. J Pediatr 1996; 128(6):855-858.
                              3.##Lamberg BA, Ikonen E, Osterlund K, Teramo K, Pekonen F, Peltola J, Valimaki M. Antithyroid treatment of maternal hyperthyroidism during lactation. Clin Endocrinol (Oxf) 1984; 21(1):81-87.
                              4.##Rylance GW, Woods CG, Donnelly MC, Oliver JS, Alexander WD. Carbimazole and breastfeeding. Lancet 1987; 1(8538):928.
                              5.##Azizi F, Khoshniat M, Bahrainian M, Hedayati M. Thyroid function and intellectual development of infants nursed by mothers taking methimazole. J Clin Endocrinol Metab 2000; 85(9):3233-3238.

                              I hope this helps. If you have any other questions please call the InfantRisk Center at 806-352-2519. Thanks,

                              Sandra Lovato R.N.
                              InfantRisk Center
                              Last edited by Sandra; 09-30-2015, 08:25 AM.