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Mary Shomon

Converting from One Thyroid Drug to Another

By January 25, 2007

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If your doctor is converting you from one thyroid drug to another, for example, Synthroid to Armour, or Thyrolar to Levoxyl/Cytomel, he or she will need to handle a dosage conversion. Click here for a chart that shows approximate equivalent doses of the drugs to help you compare the various medications.

Source: United States Pharmacopoeia Drug Information 2000, 20th Edition, Drug Information for the Health Care Professional; Vol. 1, pp. 2980-2986. World Color Book Services, Versailles, KY.

January 26, 2007 at 8:54 am
(1) Ljiljana George says:

When I changed medication from levothyroxin 100,to Armour Thyroid, my dossage was 82.5. TSH was not stable and it was high. I gained 10 pounds and kept them for as long as I was on Armour Thyroid. Endocrinologist changed this all to Synthroid 100, and Cytomel 5. I feel good. It took seven years to get here, and I am glad I made it, because many times I did not feel like I would.


January 26, 2007 at 9:17 am
(2) Nancy Chambers says:

I’ve been on various brands and doses of thyroid medicine and finally after 4 years and 3 doctors later I found a brand that doesn’t cause diarrhea, insomnia and excessive sweating and if I switch brands/manufacturers I’m back to the same problems. The doctors think that I’m allergic to the dyes & fillers used in the various brands. The only brand that works is generic manufactured by Sandoz, white(dyeless).05 Levothyroxin. If I switch manufacturers I have the same allergic problems and most HMO’s and pharmicies do not use that manufacturer. Someone should do something to standardize the meds

May 7, 2011 at 3:06 am
(3) Stella says:


Have you ever used Cytomel by Sandoz and can you tell me what the pills look like? I bought pills which came in a plastic package with no indication of a manufacturer, and the website from which I bought them claim that these are pills made by Sandoz. However, they have no imprint on them, just white round pills and I am doubtful whether they are really what I am told they are. Would be great if you could help!

Thanks !


January 26, 2007 at 9:29 am
(4) RWRAY says:

My doctors converted me from Armour Thyroid to Synthroid because 1) they say consistency of dose is better with Synthroid and 2) my Primary Care Physician didn’t know the conversion equivalents. When I asked to be converted back because of wishing to be treated with “natural” rather than synthetic products, that’s what they told me.

January 26, 2007 at 9:53 am
(5) Anna Trafford says:

I was taking 165 mcg of levothyroxine, my THS was a bit too low but still sufferef from aching legs and brain fog. I’ve now switched to taking 125mcg Thyroxine and 10 mcg Liothyronine and feel a lot better; awake and stronger! This was a couple of months ago, so I’m hoping it stays that way.

January 26, 2007 at 9:56 am
(6) Karen says:

Well I had thyroid cancer in 1999 and after surgery I was put on synthroid automatically as if there were no othere choices. After about a year of feeling awful everyday, I started searching the internet for information. I finally insisted that my doctor let me try Armour. It has been great! It took about 2 months for me but I now feel like my old self again. I will never switch back to synthroid.

January 26, 2007 at 11:43 am
(7) Ann Rz says:

my doctor had written for synthroid – they gave me generic at the pharmacy – I was on that for a few months without change – when we realized it -we switched to brand name only and now my throid goiter is shrinking and the nodules are gradually diminishing in size and disappearing -thank goodness – no more thoughts on thyroid surgery -also with the help of bi-weekly acupuncture and reflexology and B vitamins along with the synthroid – I have begun to feel more energetic and able to have a more fulfilling life!

January 26, 2007 at 11:44 am
(8) Ginny R. says:

I take naturethroid due to my allergies to many chemical additives and medications in general. I never see naturethroid mentioned, only Armour. I understand naturethroid has less additives than Armour. Why not mention it? It’s rather inexpensive, too, since health plans don’t cover it. I did have to go to a naturepath physician to get it, since health plan doctors don’t prescribe it. That costs me about $50 a year to see that physician and renew the prescription.

January 26, 2007 at 12:44 pm
(9) Leigh J says:

After playing around with dosages, 75mcg of Levoxyl plus 12.5mcg Cytomel seems to control most of the symptoms from Hashimoto’s. However, I now have started to lose hair again and had a major weight gain in the past couple of months…weight does not come off even with exercise, riding the horse and dieting. Very frustrating

January 26, 2007 at 12:45 pm
(10) Conie says:

I took synthroid for years, not knowing there were other thyroid medications.
Then I learned about Armour. I now take 50 synthroid and 30 Armour and feel tremendously better. I wish I known about it 20 years ago.

January 26, 2007 at 1:54 pm
(11) Virginia Cannon says:

After years of trying many of the thryoid meds my chiropractor tested me on Naturethroid. It has been a good choice and solved many of the issues none of the other meds did. It is a glandular like Armour (which has both T3 and T4 activity) but with less allergic response. I combine it with a small dose of compounded T4. I recommend looking at the website for “Naturethyroid” (Western Pharmaceducial) as an option to Armour or the other Rx’s out there.
I too hope it gets more attention from both mainstream and holistic medicine.
I checked many pharmacies before I found a couple that carried it.
Virginia J.

January 26, 2007 at 5:16 pm
(12) Maureen O'Neill says:

I love this website but, living in Australia, it can be hard to get the right info on drugs and dosage rates. For example, “Armour” is not available in OZ, but “natural desicated thyroid extract” is, which I get made up by a compounding pharmacist, due to my severe chemical and food intolerances. Whilst I have had an enormous improvement on medication (I have had undiagnosed Hashimotos for about thiry years and was very ill and thought that I was dying when finally diagnosed) it is extremely expensive and I still have symptoms. I would like to trial a synthetic brand but we do not have the same brand names. I went to Mary’s conversion chart, only to find that I did not recognise any of the brand names, and so am none the wiser. Does anyone know what the conversion woud be from dessicated thyroid to “Oroxine”? I would be very grateful for any help with this.

January 26, 2007 at 6:51 pm
(13) June Russell says:

With so many health problems, how can you possibly know if changing thyroid medications would help? I have had every test in the book (also TSH) by a top nutritionist/doctor, but hav8ng a hard time with symptoms.

June Russell – russells@cstone.net

January 26, 2007 at 6:51 pm
(14) June Russell says:

With so many health problems, how can you possibly know if changing thyroid medications would help? I have had every test in the book (also TSH) by a top nutritionist/doctor, but having a hard time with symptoms.

June Russell – russells@cstone.net

January 28, 2007 at 5:31 am
(15) juliet says:

In Oz the synthetic Oroxine (T4) is
Thyroxine sodium, so Maureen, use the conversion for the Levo Thyroxine on Mary’s chart. I use a combo of Oroxine and thyroid extract in Oz now.There are some good compound pharmacies that are not expensive here. I pay about AUD$34 for 100 caps of 15mg extract.

January 28, 2007 at 11:58 pm
(16) DB-KISA says:

I’ve been on 4 grains of Armour and another 25 mcg of Cytomel for several years now, but when I started on a nutritional supplement, I found myself going way hyper and I’m now down to a grain and a half plus the Cytomel. Point of this post being that some of us are off even the charts where the people who are off the thyroid test charts come to find help…

February 8, 2007 at 4:01 pm
(17) Gail says:

Over the last 7 years I have been on numerous meds, natural and synthetic. Had RAI. It appears the doctor’s are guessing. Presently I have lost 2/3 of my hair and it is like straw, weight gain appears under control at this moment but have gained 25 pounds over these years and am slowly loosing it. I get tingling throughout the day. Is this normal? It’s been like this for years. Good hours and bad hours each day. I’m on Cytomel 1/2 tab of 25 mcg and Thyrolar 25 mcg a day. 1/2 tab Cytomel and 1/2 tab Thyrolar in AM and other 1/2 Thyrolar PM. Was on 137 mcg Synthroid a month ago. Felt good first week and a half then the second week had heart racing and trouble swallowing. Called the doctor and he relayed through the nurse “it has nothing to do with the thyroid or medicine”. Seeing a new doctor next week. Synthroid slowed down the hair loss, puffy eyes, and weight puffiness while on it. Help from anyone. I’d appreeciate any insight.

September 4, 2008 at 12:11 pm
(18) Kaylee says:

When first DX’d 8 yrs ago – enlarged thyroid, 7 nodules & goiter they of course put me on Synthroid – I knew nothing and when the Endro added cytomel – I figured it was time to research and find out what I had and what I was taking for med.

That is when I found Mary’s site and then the other thyroid forums, adrenal and iodine forums….

Problem is I still didn’t feel right and labs would never optimize. I finally convinced the Endro to give me Armour.

2 years ago my TSH started dropping and even with cutting my Armour from 4 grains to 2 grains it came back totally suppressed at >.005.

At that point he found a tumor on my pituitary and slowly moved back up to 3.75 of Armour.

I just changed Endro’s due to ins. and not getting any better. Even though I called twice to make sure she writes Armour; when I got to the appt she spent what little time we had explaining the evils of armour.

According to Mary’s chart: 3.75 grains = 225 mg’s which should = 375 mg’s of Synthroid!!! I’m on 75 and want to fall flat on my face right now after a week of this!! I don’t even see her until next week.


June 12, 2009 at 11:34 pm
(19) SHERRY says:

I’ve been on levothyroxin 137MCG for about 2 years. My recent blood test showed my thyroid to be a little low, The Dr. changed my MCG to 125MCG. For lower thyroid shouldn’t my #s be higher???

February 3, 2010 at 12:18 pm
(20) BROOKE,PHARM.D. says:


June 9, 2012 at 1:54 am
(21) Melissa says:

Research “Gluten Sensitivity and Thyroid”. And don’t listen to your dr if he tells you that you can eat whatever you want when you have a thyroid condition…

December 8, 2012 at 5:02 am
(22) Dudezelle says:

How much naturethroid is equivalent to 150mg of synthetic hormone.

February 20, 2013 at 6:26 pm
(23) Gale says:

Brooke, Thank you for your comment.
What chart/source do you recommend? Also can you recommend chart/ source for dosing with total depletion? I have pituitary dysfunction w/ THS 0.01, I think I am being over medicated.
Thank you, Gale

July 21, 2013 at 6:58 am
(24) Lisa says:

I was taking 50 mcg Synthroid and 5 mcg Cytomel each morning. I am now taking 30 Armour( for 3 weeks) and I am exhausted. My skin is extremely dry, my. Head itches and my arms itch. I am thinking I need more Armour?

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