If you are taking T4 Levothyroxine thyroid medication (typically Oroxine, Eutroxsig, Eltroxin or Levoxine in Australia) for hypothyroidism due to Hashimoto’s disease, chances are you’ve experienced some lingering symptoms despite being told your TSH or T4 levels are “in range.” The truth is, there’s more to thyroid health than simply having enough T4 in your system. How well your body absorbs and converts that T4 into its active form, T3, is absolutely key to feeling better.

I know it might be considered ‘out of my lane’ to discuss medications but please understand I am not advising on dosages or whether or not you should be taking meds (see your prescribing doctor for that) but I will happily discuss optimising your T4 medication absorption because people often take it incorrectly. There are also factors that can help it to convert more effectively in your system that are very much within my realm of expertise and frankly, I want you to feel better so if this helps then, hooray!

So, so often I find my clients are taking their thyroid medication and then having breakfast and supplements 20 minutes later.

Here’s what you need to know to get the most out of your thyroid medication:

Timing is Everything

For optimal absorption, T4 medication should be taken:

• On an empty stomach, at least 30 but preferably 60 minutes before breakfast or 3-4 hours after your last meal. Depending on what you have for breakfast this may be even more important, see below. You can drink water in the 60 minute window after taking your medication.
• Away from coffee—it’s tempting, but your morning latte will reduce absorption. Wait 60 minutes after taking your medication to ensure it’s not affecting absorption. This is especially true if you take cows milk or calcium fortified milk alternatives as calcium binds to thyroxine in the digestive tract and impedes absorption.
• Separate from supplements like iron, calcium, and magnesium. Anything higher than food doses can interfere with absorption and should be spaced at least four hours apart from your T4 meds – yes, four hours!

Storage Instructions

Read packaging and follow storage instructions. Some medications need to be stored in the fridge to remain active. If you’re going away for the weekend without access to a fridge then take only what you need and leave the rest in the fridge at home. 2-3 days out of the fridge won’t be a problem. If you’re going away for several weeks you’ll need to plan ahead, store meds in a lunch bag with freezer bricks until you can get to a fridge, set alerts on your phone. Moving around can be tricky, I’ve made this mistake – I wonder if the Disneyland Paris resort still has my T3 meds in their fridge from 2016? Oops.

Night Time Dosing

Some people find taking their medication at night, 3-4 hours after dinner and before bed, works better for them, especially if mornings are chaotic. Research suggests night time dosing may improve absorption, but it’s not for everyone—give it a try and see how you feel. I’ve had some clients feel worse trialling this. If you can’t live without a dose of magnesium before bed then this won’t work for you either as T4 needs to be taken 4 hours apart from magnesium supps, see above.

The Great Conversion Problem

Even if your T4 levels look perfect on paper, your body might struggle to convert T4 into the active T3 hormone—a critical step for energy, mood, and metabolism. Your body needs to convert T4 into it’s more active form T3 in order for it to get into cells and do it’s job. This active hormone has a long list of responsibilities including metabolism, temperature regulation, energy production, not to mention important roles in cardiovascular, bone, brain, reproductive, digestive and muscular health and function. So let’s take optimising your meds a step further by looking into what can help you not only improve absorption but make the most out of conversion.

Several factors can interfere with the conversion process, including:

Genetic factors: Some people have genetic variations such as deiodinase genes (DIO1, DIO2, DIO3) that reduces their ability to convert T4 into T3. They may do better on a T3 or T4/T3 mix of medication.
Age: Conversion efficiency naturally declines as we get older.
Mineral deficiencies: Optimal levels of selenium, zinc & iron are essential for T4-to-T3 conversion, I advocate for getting these nutrients (in addition to iodine) checked annually in hypothyroidism for best outcomes.
High oestrogen: Excess oestrogen increases levels of Thyroid Binding Globulin (TBG) which bind to T3 leaving them inactive and disrupting conversion.
High cortisol: Chronic stress will undoubtedly affect conversion. You must get sick of hearing about all the ways stress wreaks havoc on your system but it’s sadly true. If you want to feel good despite your diagnosis or to improve thyroid function, you need stress coping strategies.
Poor gut and liver health: Both play a big role in thyroid hormone metabolism. In fact, 60% of T4 to T3 conversion occurs in the liver. Addressing gut dysbiosis, liver congestion, and inflammation can improve conversion. If you improve gut health then you also improve thyroxine absorption and uptake. Win, win! This is a big topic I’ll explore more in my next blog post but believe me when I tell you that liver and gut health are crucial foundations to improving thyroid function whether you take medication or not.

Discuss Treatment with your GP

While T4 (levothyroxine) is the most commonly prescribed thyroid medication, not everyone converts T4 effectively into T3. If you still have symptoms despite taking T4:

• Ask your doctor if you’ve ever tried T3 medication (liothyronine), which is already in its active form.
• Ask your doctor about Natural Desiccated Thyroid (NDT) medication. Made from porcine thyroid glands, NDT contains both T4 and T3, along with other thyroid hormones. Some people feel significantly better on this option, but it’s not for everyone. Not all GP’s will be aware of this option and you need a compounding pharmacist to have a script filled because it is not a synthetic pharmaceutical in the traditional sense.

FYI: Levothyroxine has a half-life of about 7 days.

The Bottom Line

If you’re still struggling despite following all of the above, it’s worth digging deeper into potential drivers like nutrient levels, gut health, emotional wellbeing or hormonal imbalances.

I recommend you focus not just on the numbers on your pathology results but how you feel. Energy, cold tolerance, mental clarity, digestion, hair, nails etc will all give you clues as to how well your thyroid is performing. One of the easiest ways to track this is via basal temperature tracking. For a few days in a row per month, check your temperature upon waking before getting out of bed, preferably at the same time each morning. A healthy basal temperature is 36.5-36.9. Anything lower and it may indicate you are not getting enough T3.

Managing thyroid health is about more than just swallowing a pill. By optimising how you take your T4 medication and addressing issues that may be affecting conversion you can give yourself a better chance of feeling your best.

Please share this blog with loved ones taking thyroid medication in case they aren’t aware of the above factors.