Levothyroxine, a thyroid hormone medicine, is usually taken once a day on an empty stomach, a set time before breakfast, and the directions on your prescription label are the ones to follow. With breakfast gone from your mornings, the tablet still needs that empty stomach. Ask the pharmacist who fills it how the wait applies to whatever you now eat first, and check the supplements and foods that now share your mornings against the tablet.
Does the tablet's timing depend on breakfast?
The tablet's timing is tied to an empty stomach as well as to breakfast: the instruction is to take it on an empty stomach, before breakfast, and breakfast is usually the first food that follows. Some medicines need to be taken when your stomach is empty because food or drink can affect how they work, and levothyroxine is one of them. Your doctor may recommend taking it in the morning before eating, which asks for the same thing without naming a meal.
For medicines in general, an empty stomach generally means taking the medicine at least two hours before you eat or two hours after you eat, and that is only a rough guideline. Levothyroxine has its own, drug-specific wait before breakfast, so follow the directions on your prescription label, and ask your doctor or pharmacist to explain any part you do not understand. Only the doctor who prescribes it can change those directions.
Tell the pharmacist who fills your levothyroxine whether the first thing you eat is now a snack later in the morning or lunch, and ask whether a drink you still have on waking, such as coffee, counts against the wait.
Take the tablets with a full glass of water, as they may get stuck in your throat or cause choking or gagging. If your morning drink used to arrive with breakfast, keep the glass of water with the tablet all the same.
Other things in your new mornings that can interfere with the tablet
If calcium carbonate (Tums) or ferrous sulfate, an iron supplement, is now part of your mornings, keep it apart from levothyroxine, before or after it, by at least a set number of hours. If you take cholestyramine, colesevelam, colestipol, sevelamer or sodium polystyrene sulfonate, take it after levothyroxine, again by at least a set number of hours. Ask the pharmacist who fills your levothyroxine for both numbers.
Some nonprescription products may interact with levothyroxine:
- proton pump inhibitors, which reduce stomach acid
- antacids
- simethicone, an anti-gas medicine
- aspirin and other salicylate pain relievers
- niacin
- nonsteroidal anti-inflammatory medicines (NSAIDs), such as ibuprofen and naproxen
If you already take one, tell your levothyroxine prescriber and your pharmacist. Before you start any of them, talk it over with that doctor or your pharmacist first.
Talk to your doctor before eating or drinking foods that may affect how levothyroxine works for you, particularly those that contain soybeans, walnuts and dietary fiber. Fiber is in a great many foods, so the useful step is to tell your doctor what has taken breakfast's place: read the ingredients of a shake or a bar for soy, walnuts and fiber, and mention any fiber supplement too. Grapefruit and grapefruit juice are also something to talk over with your doctor while you take this medicine, so raise them in the same conversation.
If you have Hashimoto's disease or another autoimmune thyroid disorder, you may be more easily harmed by iodine's side effects. Foods with large amounts of iodine, such as kelp, dulse or other seaweed, may cause or worsen hypothyroidism, and iodine supplements can have the same effect. Ask your levothyroxine prescriber which foods to limit or avoid, and tell them about any iodine supplement you take and any cough syrup, since cough syrups may contain iodine.
Tell your doctor and pharmacist about every prescription and nonprescription medicine, vitamin, supplement and herbal product you take or plan to take with levothyroxine, because your doctor may need to change the doses of your medicines or monitor you carefully for side effects. If a weekly weight medicine is part of why you eat less, your levothyroxine prescriber needs to hear about it (see A weekly weight medicine can change how some of your other tablets work).
Can you tell a thyroid problem from the way eating less makes you feel?
Not on your own. The way you feel while eating less cannot show whether a thyroid problem is behind it: many of the symptoms of hypothyroidism are the same as those of other diseases, which is why a diagnosis can't rest on symptoms alone. Some complaints appear both as symptoms of an underactive thyroid and as side effects of levothyroxine itself:
| Among the common symptoms of an underactive thyroid | Among the side effects of levothyroxine |
|---|---|
| weight gain | weight gain or loss |
| dry skin or dry, thinning hair | hair loss |
| joint and muscle pain | joint pain |
| heavy or irregular menstrual periods or fertility problems | changes in menstrual cycle |
The rest of each list does not pair up:
- the common symptoms of an underactive thyroid also include fatigue, trouble tolerating cold, a slowed heart rate and depression
- levothyroxine's other side effects are changes in appetite, headache, vomiting, diarrhea, fever, sensitivity to heat and leg cramps
Many symptoms of an underactive thyroid, especially fatigue and weight gain, are common and do not necessarily mean you have a thyroid problem. Raise any of them that worries you with your levothyroxine prescriber, along with a side effect of levothyroxine that is severe or does not go away, and leave it to that doctor to decide whether a blood test is due.
Signs that need your doctor immediately, or emergency care
If you have any of the following while taking levothyroxine, call your doctor immediately or get emergency medical treatment at an emergency room or through 911:
- chest pain
- rapid or irregular heartbeat or pulse
- uncontrollable shaking of a part of the body
- nervousness, anxiety or irritability
- difficulty falling asleep or staying asleep
- shortness of breath or wheezing
- excessive sweating
- hives, itching, rash or flushing
- stomach pain or nausea
- swelling of the hands, feet, ankles or lower legs
For severe chest pain or pressure, or severe shortness of breath, call 911 to have the emergency team come to you right away rather than ringing the doctor first.
If someone has taken too much levothyroxine, call the Poison Help line at 1-800-222-1222, and call 911 immediately if they have collapsed, had a seizure, have trouble breathing or cannot be woken.
Who can change the prescription, and what tells them to
The doctor who prescribes your levothyroxine is the one to change the prescription, and they check the dose with a blood test. If you take thyroid hormone medicine because of hypothyroidism or because your thyroid was removed, you'll have regular TSH (thyroid-stimulating hormone) tests to check that you are taking the right dose, though a TSH test can't show what is causing a thyroid problem.
Once you've reached a dose that's working for you, your doctor will probably repeat the blood test in 6 months and then once a year, with another test each time your dose is adjusted. Ask that doctor whether your next test is due, and mention that breakfast has dropped out of your mornings. Before the test, tell the doctor ordering it about everything you take, because you may need to stop certain medicines first, and stop one only if that doctor tells you to.
Never stop taking your thyroid medicine without talking with your doctor first. Taking too much of it can cause serious problems, such as an irregular heart rhythm called atrial fibrillation, or thinning bones (osteoporosis), and levothyroxine is not to be used, alone or with other treatments, to treat obesity or cause weight loss; in large doses it may cause serious or life-threatening problems, especially when taken with amphetamines.
Levothyroxine is usually a pill, and it also comes as a liquid and as a soft gel capsule, newer forms that may help people with digestive problems absorb the thyroid hormone. The doctor who prescribes it decides which form you take, so tell that doctor about any digestive problem you have, including a stomach you have been told empties slowly (see Gastroparesis diagnosed years ago still matters for a weekly injection).
According to NIDDK, part of the National Institutes of Health, thyroid medicines are safe to take during pregnancy and can help prevent problems, while hypothyroidism left untreated during pregnancy can affect both mother and baby. Many women taking thyroid hormone medicine need a higher dose during pregnancy, so contact your levothyroxine prescriber right away if you find out you're pregnant. Tell that doctor too if you plan to become pregnant or are breastfeeding.
A physician holding a license in your state decides on weight treatment through NicoCares. If your appetite changed during that care, tell your care team there about the levothyroxine, with a line on how your mornings run now, in a message on Spruce, the secure messaging app where the team answers patients. Spruce messages carry no promise of when an answer will come, so the warning signs above go to your levothyroxine prescriber, an emergency room or 911, and an overdose to Poison Help or 911, never to Spruce.
