What is the difference between eltroxin and thyroxine

Food and Drug Administration FDA has also approved the use of generic levothyroxine, which is now made by a number of different pharmaceutical companies. Most drugs do not differ much in their generic and brand name forms, so switching between the two is not a big issue.

Levothyroxine, however, is one of a handful of exceptions. Manufacturers of any preparation of levothyroxine must ensure that their drug is within 5 percent of its stated potency, which must be between 95 percent and percent , per the FDA.

This leaves room for meaningful differences between your levothryoxine options. Given that the FDA allows such variation, it's easy to think that it can't have much effect. But levothyroxine has what's called a "narrow therapeutic window," meaning that treatment must be fine-tuned in order to achieve the desired effects. Though the potency of one levothyroxine option may seem marginally different than another, the discrepancy could lead you to take anywhere from around a half a pill less or an entire pill more over the course of a week if you make a switch—even if you're taking the same dosage as you were before.

This can dramatically influence your thyroid disease management. Brand name levothyroxines are consistent in terms of potency from batch to batch.

Generic formulations, on the other hand, tend to be less so. If you switch from a brand name to a generic preparation, you may notice that you don't feel as well on the generic drug and may have symptoms of hypo- or hyperthyroidism.

While this can be due to the drug's dosage and potency, it can also be due to:. Some people are especially prone to exacerbated symptoms when making any change to their thyroid drug regimen. While the chemical structure and safety profiles of brand-name and generic versions themselves are the same, even a small difference in dosage strength can cause symptoms, which must be considered, especially if you are dealing with thyroid disease-related complications or co-occuring conditions, like heart disease.

In addition, additional ingredients found in different versions of levothyroxine may pose safety concerns for people with allergies or sensitivities. Fillers and additives such as dyes, gluten, and lactose are also less consistent in generics than brand-name options because they originate from different manufacturers.

If this is a concern for you, ask your pharmacist for a list of your prescribed drug's ingredients. Additional chemicals added to drugs are usually considered "inert" or "inactive," but studies have found that these inactive ingredients can sometimes decrease the effectiveness of a particular drug. Of course, unpleasant symptoms may be a coincidence or due to some other health problem.

If you are certain that you need to stick with a particular brand of levothyroxine, make sure your healthcare provider writes "DAW" and "no generic substitution" on your prescription.

According to a presentation at the annual meeting of the American Association of Clinical Endocrinologists in , Synthroid was associated with significantly better thyroid-stimulating hormone TSH lab results than generic levothyroxine.

The study authors looked at hypothyroidism patients between January and March who were started on either Synthroid or generic levothyroxine within a year of being diagnosed. During follow-up, the final TSH lab outcomes were out of range for In general, however, studies comparing generic and brand name formulations of levothyroxine fail to definitively show the advantages of one preparation over another.

For example, one study found that more than 80, new thyroid patients taking brand-name or generic levothyroxine for a year had the same risk of cardiovascular issues requiring hospitalization e. But there are plenty of anecdotal reports of people who have switched formulations—and felt better as a result of the change—that differences can't be dismissed entirely. The American Association of Endocrinologists recommends taking the same brand or generic type of medication throughout your treatment.

The Association emphasizes that "thyroid disease often requires lifelong therapy and is best managed with consistent and precise treatment with the same brand of thyroid hormone. Despite this, there are some individuals for whom generic levothyroxine may not be advised. In particular:. If these situations don't apply to you and you decide that changing to a generic is the way to go for cost-saving reasons, be sure to speak with your healthcare provider about a recommended schedule for checking your TSH levels.

Get our printable guide for your next doctor's appointment to help you ask the right questions. Other tips for successfully transitioning to a generic include:. Whether it is a brand name or generic form of levothyroxine a person receives, some people continue to experience symptoms of hypothyroidism even when their TSH is normal. Hypothyroidism can be treated with levothyroxine, the main hormone secreted by the thyroid gland. There are different manufacturers that make levothyroxine.

When levothyroxine is generic non-branded , prescriptions may be filled with levothyroxine from different manufacturers. Because potency of levothyroxine between manufacturers is variable, there is a possibility that changing brands may affect thyroid function tests.

However, there is limited data on the impact of changing brands on thyroid function. In , the manufacturer of the levothyroxine brand Thyrax experienced an interruption in production that required approximately , Dutch patients to change their levothyroxine supplier.

Levothyroxine which is also called levothyroxine sodium restores the balance of thyroid hormone in your body. It is very similar to thyroxine, the hormone which your body produces naturally. Some medicines are not suitable for people with certain conditions, and sometimes a medicine may only be used if extra care is taken.

For these reasons, before you start taking levothyroxine it is important that your doctor knows:. Along with their useful effects, most medicines can cause unwanted side-effects although not everyone experiences them. The table below contains some of the ones associated with levothyroxine. You will find a full list in the manufacturer's information leaflet supplied with your medicine. Experiencing side-effects may be an indication that your dose needs adjusting, so speak with your doctor if you experience any of the symptoms listed below.

If you experience any other symptoms which you think may be due to this medicine, speak with your doctor or pharmacist. Never take more than the prescribed dose. If you suspect that you or someone else might have taken an overdose of this medicine, go to the accident and emergency department of your local hospital.

Take the container with you, even if it is empty. This medicine is for you. Never give it to other people even if their condition appears to be the same as yours.