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Finding the right medication is one of the cornerstones of treatment for an underactive thyroid (hypothyroidism). Thyroid hormone replacement therapy replaces the thyroid hormones that are not being produced by the thyroid gland in the case of hypothyroidism. Still, even when you've found the right thyroid hormone replacement, it's essential to know how and when to take it for the best results. Let's review what you need to know.
Getting the best results from your thyroid hormone replacement medication starts when you pick up your thyroid medicine from the pharmacy. Whether you're starting a new medication or picking up a refill, be sure to check the label to confirm you're getting:
- The correct medication
- The correct dosage
- Unexpired drugs
- The right number of pills
You may also want to check for substitutions as different brands contain the same active ingredient but may have other filler ingredients that affect absorption.
It can take some time to determine the proper daily dose of thyroid replacement hormone. After you start a new medication, it's advisable to test your thyroid function after six to eight weeks to determine if you're on the correct dose of thyroid hormone.
Taking excess thyroid hormone can cause side effects that mimic hyperthyroidism (overactive thyroid), like:
- Increased appetite
- Irregular heartbeat
Thyroid medication shouldn't cause adverse effects when used in the appropriate dose. If your pharmacy changes your brand, you have the right as a patient to tell them you want exactly what your doctor prescribed. Still, if you do change brands, let your doctor know to ensure you're still getting the proper dosage.
Typically, instructions recommend taking your thyroid medication in the morning, on an empty stomach, an hour before eating or drinking coffee, milk, grapefruit juice, and three to four hours before taking supplements or medications that contain iron or calcium.
Still, the most important guideline is to take your medication consistently at the same time every day—whether you're receiving treatment with levothyroxine, liothyronine (Cytomel), natural desiccated thyroid, or compounded medication.
You may want to talk to your healthcare provider about taking levothyroxine at bedtime. Published research has found that this enhances absorption of levothyroxine, as seen in significantly improved levels of thyroid hormone. Taking levothyroxine medication at night gives you more freedom to eat, drink, and take supplements first thing in the morning.
An important note: if you switch between taking your thyroid pills in the morning and evening, you should have your thyroid hormone levels retested, as a possible change in absorption may require an adjustment to your dose.
Some patients may be tempted to split tablets using a pill cutter, either to save money or take partial doses. You should be aware that experts don't typically recommend splitting levothyroxine tablets or liothyronine tablets (Cytomel). The drug's narrow therapeutic index and uneven distribution of the active ingredient mean that you can't guarantee dosage consistency.
If you're taking a combination therapy that includes T3 like liothyronine (Cytomel), natural desiccated thyroid, or a T4/T3 compounded medication, talk to your health care provider about whether divided doses make sense for you. Because T3 is fast-acting, dividing your dose can help even out spikes and dips in T3 levels and prevent overstimulation. For example, dividing a 10 mcg T3 per day dose into 5 mcg in the morning and 5 mcg an hour after lunch, or dividing a 2-grain dose of natural thyroid into 1 grain of natural thyroid in the morning, ½ grain in the afternoon, and ½ grain after dinner.
Ideally, you should swallow your thyroid medication with water.
Suppose you're taking levothyroxine solution like Tirosint-SOL. In that case, you can take the liquid medication directly into your mouth or add the ampule contents to a glass of water and drink all of it immediately.
One additional note: you may have seen recommendations to chew your thyroid medication or let it dissolve sublingually under the tongue. It's not recommended for levothyroxine tablets, and there's no evidence that this improves the effectiveness or absorption of levothyroxine. Some patients, however, anecdotally report better results when taking natural desiccated thyroid drugs this way.
If you plan to change how you take your thyroid medication, always talk to your health care provider.
The chart below summarizes the general recommendations regarding how long to wait between specific foods, drinks, and supplements and when you take your thyroid hormone replacement drugs.
For more information, read "Seven Things That Can Affect Your Thyroid Medication."
The issue of food
Some people can't take their thyroid medication on an empty stomach for various reasons. If you fall into this category, remember that the key is consistency. Always take your medication the same way every day—whether with or without food—so that your thyroid test levels are consistent.
Proton Pump Inhibitor (PPI) drugs like Prevacid and Prilosec, for acid reflux and other gastrointestinal issues, can generally interfere with absorption of thyroid medication at whatever time of day you take them. To minimize potential drug interactions, consider taking a liquid form of levothyroxine (i.e., Tirosint-SOL), which studies show has the least absorption impact from PPI drugs.
Biotin (Vitamin B7) is typically found in high doses in megavitamin B complex and combination formulas to support hair, skin, and nails. Biotin can make T4 and T3 look artificially high and the TSH artificially low. That's why the American Thyroid Association recommends stopping biotin for at least two days before traditional laboratory thyroid blood testing to avoid false results.
Note that the Paloma Health at-home thyroid test kit does not require you to stop taking biotin.
Many patients wonder whether to take thyroid pills before thyroid testing.
If you are taking levothyroxine alone, it doesn't matter whether you've taken your medication or not, as your levels won't fluctuate dramatically throughout the day.
If you are taking a T3 medication, consistency is vital so you and your provider can accurately compare results from test to test. First, talk to your doctor, and find out their preferences. They may prefer you to get test results before or after taking your medication and make sure you're both in agreement. (Note: many providers prefer that you take your medicines before testing to assess your Free T3 levels with medication.)
No matter when you take your T3 medication in regards to testing, aim to both take the medicine and test your thyroid simultaneously.