The information presented here is intended for educational purposes only. It is not intended, nor should it be interpreted, as medical advice or directions of any kind. Any person viewing this information is strongly advised to consult their own medical doctor(s) for all matters involving their health and medical care.
- Wherever you obtain your prescriptions, always double check your pills when you receive them to be sure that you are getting what your doctor prescribed. Do this for all of your prescriptions, not just levothyroxine.
- Levothyroxine is the pharmaceutical name for synthetic thyroid hormone (T4) prescribed for people who have been treated for thyroid cancer. Several brand-name synthetic levothyroxine preparations are currently available. These include Levothroid, Levoxyl, Synthroid and Unithroid in the United States; Eltroxin and Euthyrox in Canada; and a gel-capsule in blister packs: Tirosint.
- Although all these medications are synthetic levothyroxine, they are not identical. The manufacturing processes differ, as do the fillers and dyes. These differences may affect the absorption of the drug. The absorption affects how much of the drug your body actually receives.
- For this reason, thyroid cancer specialist physicians recommend that thyroid cancer patients consistently take levothyroxine from the same manufacturer. If you need to change manufacturers for some reason, you should have your thyroid levels checked 6-8 weeks later, because your TSH may have changed and no longer be at the level recommended by your physician.
- Thyroid cancer patients should be very careful when having their prescription filled, because some pharmacies and some health insurance plans allow switching from the brand that the patient was taking to a generic.
A generic prescription means the pharmacist could potentially fill the prescription with one manufacturer’s levothyroxine one month and use another manufacturer the next month. Because of absorption differences, a change in manufacturers can result in a change in your TSH level. Always know which manufacturer you are using. Make sure that your prescription specifies the brand name or the word levothyroxine followed by the name of the manufacturer.
Also, make sure that your prescription is marked “Dispense as written” or “Do not substitute.” This extra effort by you and your physician will make it clear to the pharmacist or pharmacy technician exactly what you need.
If you encounter a pharmacy technician or pharmacist who insists that you can change manufacturers, tell them that because of your thyroid cancer, you need to stay on the same brand as part of your thyroid cancer management and that thyroid cancer specialist physicians recommend against brand switching due to the effect on TSH and the resulting need for additional blood testing.• ThyCa and its medical advisors do not recommend any particular brand in preference to other brands. For statements by endocrinology associations, ThyCa, and the U.S. Food and Drug Administration during 2004 and 2005 regarding therapeutic equivalence and brand switching, visit this page of the ThyCa web site: http://thyca.org/news/levothyroxineproducts.htm. If you don’t have Internet access, please send a self-addressed, stamped envelope to ThyCa, Inc., Attn: Therapeutic Equivalence, P.O. Box 1545, New York, NY 10159-1545 and we’ll mail you a printed copy.
- Also, check prices and co-payments. Prices vary among pharmacies and sometimes the cost of the pills is lower than the co-payment.
- Another point to remember is that levothyroxine is temperature-sensitive, especially if above room temperature. Mailing during the heat of the summer may result in lowered potency. Ordering a three-month supply at the beginning of the summer can lessen that risk. Picking up pills at a local pharmacy also helps avoid temperature extremes.
- Store your levothyroxine pills away from heat, humidity, and light. When the weather is warm or sunny, don’t leave them in a parked car, because it can become hot. When traveling, keep them from becoming exposed to heat.
- For information about taking pills, and about potential interactions between levothyroxine and other medications, visit the section of our web site titled “How To Take Levothyroxine” (http://thyca.org/pap-fol/more/levothyroxine/). If you don’t have Internet access, please send a self-addressed, stamped envelope to ThyCa, Inc., Attn: How To Take Levothyroxine, P.O. Box 1545, New York, NY 10159-1545 and we’ll mail you a printed copy.
- As with any prescriptions, read the information pamphlet that comes with your prescription. The pamphlet describes what the medicine is, how to take it, any other drug interactions or contraindications, possible side effects, and more.
- If you have any questions about any medications you are taking, ask your doctor or pharmacist for more information.
- For current information about levothyroxine and thyroid cancer management, visit the web sites of ThyCa: Thyroid Cancer Survivors’ Association, Inc. at www.thyca.org and the American Thyroid Association at www.thyroid.org.
Click here for a PDF document that also has a chart showing pill colors for each dosage.
This information sheet was prepared by ThyCa: Thyroid Cancer Survivors’ Association, Inc.
Last updated: October 10, 2011