Amiodarone inhibits peripheral conversion of levothyroxine T4 to triiodothyronine T3 and may cause isolated biochemical changes increase in serum free-T4, and decreased or normal free-T3 in clinically euthyroid patients.
In euthyroid patients, doses within the range of daily hormonal requirements are ineffective for weight reduction. Larger doses may produce serious or even life-threatening manifestations of toxicity, particularly when given in association with sympathomimetic amines such as those used for their anorectic effects.
Patient Site. Full Prescribing Information. Indication and Important Safety Information. Contact Medical Information. Hypothyroid medications require precise dosing and careful monitoring. Please enter a valid numerical weight. Please enter a valid weight using only whole numbers. Please enter a weight between 2 to 3 digits. Non-elderly, otherwise healthy individuals with hypothyroidism for a short time. Begin at full replacement dose: 1. By Elderly patients or those with underlying cardiac disease.
Severe long-standing hypothyroidism. Pregnant patients with new onset hypothyroidism: Moderate to severe signs and symptoms. Pregnant patients with new onset hypothyroidism: Mild hypothyroidism. Begin at 1. Careful dose titration is necessary to avoid the consequences of over- or undertreatment. Certain foods may decrease absorption and require dosing adjustments, including 2 : Soybean flour infant formula Cottonseed meal Walnuts Dietary Fiber Grapefruit juice delays the absorption of Synthroid and reduces its bioavailability.
Phosphate Binders. The thyroid gland in your neck makes a hormone called thyroxine. Thyroxine controls how much energy your body uses the metabolic rate. It's also involved in digestion, how your heart and muscles work, brain development and bone health. When the thyroid gland does not make enough thyroxine called hypothyroidism , many of the body's functions slow down.
Some of the most common symptoms of an underactive thyroid gland are:. Levothyroxine is a synthetic version of thyroxine. You take levothyroxine tablets to replace the thyroxine that your thyroid gland cannot produce and prevent the symptoms of hypothyroidism. Levothyroxine starts working straight away, but it may be several weeks before your symptoms start to improve and you feel any different.
Treatment with levothyroxine is usually lifelong. If you stop taking levothyroxine your symptoms are likely to come back. Yes, it's safe to take levothyroxine for a long time, even many years. High doses of levothyroxine over a long time can sometimes cause weakening of the bones osteoporosis. This should not happen if you are on the right dose. It's important to have regular blood tests to make sure your dose is not too high.
There's no clear evidence to suggest that taking levothyroxine will reduce fertility in either men or women. However, speak to a pharmacist or your doctor if you're trying to get pregnant. They may want to review your treatment. Yes, you can drink alcohol while taking levothyroxine. Alcohol does not affect how this medicine works.
One of the symptoms of an underactive thyroid gland is weight gain. So, once you start taking levothyroxine, you may lose weight as your body's hormones rebalance. Losing weight can also be a sign that your dose of levothyroxine is too high. Once your thyroid hormone levels have returned to normal, your tendency to gain or lose weight is the same as for people who do not have thyroid problems.
If you have an underactive thyroid, you're entitled to free prescriptions for all of your medicines not just your levothyroxine. To claim your free prescriptions you'll need to have a medical exemption certificate. The application form for the medical exemption certificate is called FP92A. You can get this from your doctor's surgery.
You will need to fill in the form, then your doctor will sign it and send it off. Contraceptive pills that contain oestrogen combined contraceptive pills can reduce the amount of levothyroxine in your body.
Speak to your doctor if you start or stop taking the Pill — your dose of levothyroxine may need to change. It's having an underactive thyroid that causes hair loss — not treatment with levothyroxine. Because the natural hair growth cycle takes several months, hair loss related to thyroid disease might only be seen months after the illness has begun. If treatment with levothyroxine has already started, it may seem like the medicine — rather than the underlying illness — is causing the hair loss.
Page last reviewed: 23 October Next review due: 23 October Levothyroxine - Brand name: Eltroxin On this page About levothyroxine Key facts Who can and cannot take levothyroxine How and when to take levothyroxine Side effects Pregnancy and breastfeeding Cautions with other medicines Common questions about levothyroxine.
About levothyroxine Levothyroxine is a medicine used to treat an underactive thyroid gland hypothyroidism. Levothyroxine starts working straight away, but it may be several weeks before your symptoms start to improve. The most common side effects of levothyroxine are caused by taking a bigger dose than you need. Your doctor can lower your dose to help reduce any side effects. Before you start taking levothyroxine, your doctor will do a blood test to see what dose you need.
Once you start taking the medicine you'll have regular blood tests to see how well it's working. Levothyroxine doses need to be carefully monitored during pregnancy. If you're planning to become pregnant or think you may be pregnant while taking levothyroxine, it's important to visit your doctor to make sure you get the correct care for you and your baby.
Do not take levothyroxine and go back to your doctor to discuss your treatment if you have : had an allergic reaction to levothyroxine or any other medicines in the past an overactive thyroid hyperthyroidism a health problem that affects your adrenal glands your doctor will be able to tell you if you're not sure Check with your doctor before taking levothyroxine if you have : a heart problem including angina , heart disease or heart failure high blood pressure had a heart attack diabetes — the dose of your diabetes medicine may need to change because levothyroxine can raise blood sugar levels.
Dosage You may need to take several different tablets to make up your dose. Your doctor will tell you how many tablets to take each day. The dose of levothyroxine varies from person to person. How to take it Swallow the tablets whole with a drink of water.
What if I forget to take it? What if I take too much? Taking an extra dose of levothyroxine by accident is unlikely to harm you. Speak to your doctor if: you accidentally take more than 1 extra dose you get side effects such as a racing heart beat or chest pain — these may not happen straight away, it can be several days before they come on Blood tests Your doctor will do regular blood tests to check the levels of thyroid hormones in your body before and after starting levothyroxine.
These will allow your doctor to adjust the dose to suit you. You may need blood tests more often if you: are pregnant start or stop a medicine that can interfere with levothyroxine have any symptoms that could mean your dose is not quite right. Common side effects and self-help advice The common side effects of levothyroxine usually happen because the dose you're taking is more than you need. Keep the ampules in the pouch until you are ready to use them. There is a problem with information submitted for this request.
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