Levothyroxine is one 1 of the most widely prescribed medicines in the world. It replaces the thyroid hormone that an underactive thyroid cannot make. It is cheap, safe and effective, but only when it is taken correctly. Small mistakes, such as taking it with breakfast or with iron tablets, can stop it working properly. This pharmacist’s guide explains how to take levothyroxine, so that you get the full benefit from every dose.
What levothyroxine does
Levothyroxine is a man-made version of thyroxine, also called T4, the main hormone produced by the thyroid. It is used to treat an underactive thyroid, also known as hypothyroidism. It is also prescribed after thyroid surgery, after radioactive iodine treatment and for some people with goitre or thyroid cancer.
Most people need to take it for life. Learn more about the condition in our article on hypothyroidism.
The golden rule: an empty stomach
Food reduces the amount of levothyroxine your body absorbs. For the most reliable effect:
Take it first thing in the morning with a glass of water
Wait at least 30 to 60 minutes before eating breakfast or drinking tea, coffee or milk
Take it at the same time every day
If mornings do not suit you, some people take it at bedtime instead, at least three hours after their last meal. The most important thing is consistency. Pick one routine and stick to it.
Medicines and supplements to separate
Several common products bind to levothyroxine in the gut and stop it being absorbed. Take levothyroxine at least four hours apart from:
Calcium supplements and calcium-rich antacids
Iron tablets 2 , including many pregnancy supplements
Multivitamins containing iron or calcium
Aluminium or magnesium antacids
Cholestyramine and some other cholesterol medicines
Other medicines change how the body handles levothyroxine, including some epilepsy medicines, rifampicin for TB and oestrogen-containing contraceptives or hormone therapy. Tell your doctor and pharmacist about everything you take, including herbal and over-the-counter products.
Foods and drinks to watch
Coffee, including espresso and instant coffee, can reduce absorption if taken too soon after the tablet. Soya products, high-fibre breakfast cereals and grapefruit juice can also have an effect. You do not need to avoid these foods. Simply keep the timing consistent, so that your dose can be adjusted to match your normal diet.
How long does it take to work?
Levothyroxine does not work overnight. Many people start to feel better within two to three weeks, but it takes about six to eight weeks for hormone levels to settle after starting or changing the dose. That is why your doctor will usually check your thyroid blood test six to eight weeks after any change.
Once your dose is stable, a blood test once a year is usually enough. The test measures TSH, and sometimes free T4.
Getting the dose right
The right dose depends on your weight, age, heart health and the cause of your underactive thyroid. Older adults and people with heart disease usually start on a low dose that is increased slowly.
Signs that the dose may be too high include palpitations, shaking, sweating, anxiety, poor sleep, diarrhoea and weight loss. Signs that it may be too low include tiredness, feeling cold, constipation, weight gain and low mood. If you notice any of these, contact your doctor. Do not change the dose on your own.
How to take levothyroxine with other daily medicines
Many people take several medicines each day. A simple timetable helps you learn how to take levothyroxine without clashes:
6 am: levothyroxine with water
7 am: breakfast, tea or coffee, and most other morning medicines
11 am or later: iron, calcium or multivitamin supplements
Evening: other evening medicines as usual
If you take a medicine that must be taken on an empty stomach too, ask your pharmacist how best to space them. Writing the schedule on a card or setting phone alarms makes it easier to remember.
What to do if you miss a dose
If you forget a dose, take it as soon as you remember on the same day. If you do not remember until the next day, skip the missed dose and take your usual dose. Never take two doses at once to make up for a missed one. Missing an occasional dose is unlikely to cause harm, because levothyroxine stays in the body for a long time.
HUBPHARM PHARMACIST’S NOTE If your pharmacy gives you a different brand of levothyroxine, ask for the same one next time, or let your doctor know so the blood test can be repeated. HubPharm keeps a record of your brand so your refills stay the same from month to month. We can also remind you when your next thyroid blood test is due.
Decision chart for a missed tablet, part of a guide on how to take levothyroxine
Levothyroxine stays in the body for a long time, so an occasional missed dose is not dangerous.
Switching brands
Different brands of levothyroxine are not always exactly the same. Some people notice a change in symptoms after switching. Try to stay on the same brand. If your brand changes, tell your doctor, who may check your blood test about six to eight weeks later.
Pregnancy and levothyroxine
The body needs more thyroid hormone during pregnancy. If you take levothyroxine and find out that you are pregnant, contact your doctor straight away. Many women need their dose increased early in pregnancy. Regular blood tests are needed throughout pregnancy to keep levels in the right range. After birth, the dose usually returns to the pre-pregnancy level.
Levothyroxine is safe in pregnancy and while breastfeeding. Stopping it can harm both mother and baby.
Biotin and blood tests
Biotin is a vitamin found in many hair, skin and nail supplements. High doses can interfere with thyroid blood tests, giving falsely abnormal results. Stop biotin supplements at least two days before a thyroid blood test, or tell the laboratory that you take them.
Never use it for weight loss
Levothyroxine is not a weight-loss medicine. Taking it when you do not need it, or in higher doses than prescribed, can cause dangerous heart rhythm problems and bone thinning. Only take it on a doctor’s prescription.
Storing your tablets
Keep levothyroxine in its original pack, in a cool, dry place away from direct sunlight. Heat and humidity can affect the tablets. Do not store them in the bathroom or a hot car. Check the expiry date and collect your next supply before you run out.
How to take levothyroxine when you are unwell
During a short illness, such as malaria or a stomach upset, continue taking your levothyroxine as usual. If you vomit within an hour of taking a dose, you can usually take another tablet. If vomiting or diarrhoea lasts more than a day or two, tell your doctor, because absorption may be affected. If you are admitted to hospital, take your tablets with you, and make sure the ward team knows your dose.
Common questions from patients
Can I take levothyroxine with tea? It is best to wait 30 to 60 minutes before drinking tea or coffee.
Can I stop it if I feel better? No. Feeling better means the dose is working. Stopping it will bring your symptoms back.
Will it make me gain weight? No. The correct dose helps your metabolism return to normal. Any weight gained from an underactive thyroid may slowly come off.
Learning how to take levothyroxine correctly is one of the simplest ways to feel well with an underactive thyroid. If you are unsure about how to take levothyroxine alongside your other tablets, a pharmacist can help.
Take on an empty stomach with water, 30 to 60 minutes before breakfast, at the same time daily.
2
Calcium and iron supplements
Over the counter
Take at least four hours apart from levothyroxine.
To order any of these, or to ask a pharmacist a question first, message HubPharm on WhatsApp or visit hubpharmafrica.com. Prescription medicines are supplied against a valid prescription.
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