Worst Pills, Best Pills

An expert, independent second opinion on more than 1,800 prescription drugs, over-the-counter medications, and supplements



Search results below include Disease and Drug Family Information where your selected drug is a primary subject of discussion.

Thyroid Hormone
Variations in the amount of active levothyroxine available in a tablet can affect both the safety and effectiveness of the drug. Levothyroxine is unstable in the presence of light, temperature, air, and humidity. Patients who receive superpotent tablets (too much levothyroxine) experience chest pain, rapid heart rate, or heart rhythm disturbances. There is also evidence that overtreatment can cause the bone-weakening disease osteoporosis. Subpotent (too little levothyroxine) tablets will not be effective in controlling the symptoms of low thyroid hormone production (hypothyroid).


A comprehensive review of the safety and effectiveness of this drug. If the drug is not a Do Not Use product, information on adverse effects, drug interactions and how to use the medication are included.
Search results below include Drug and Dietary Supplement Profiles where your selected drug is a primary subject of discussion.


Search results below include Worst Pills, Best Pills Newsletter Articles where your selected drug is a primary subject of discussion.

Drugs Associated with Osteoporosis and Related Fractures
January 2024
Osteoporosis occurs when there is a decrease in bone mineral density and bone quality that can weaken bones, making them susceptible to fracture easily. Learn about drugs that are associated with osteoporosis and related fractures.
Important Drug Interactions for the Stomach-Acid–Suppressing Drug Rabeprazole (ACIPHEX)
June 2023
Patients taking the stomach-acid-suppressing drug rabeprazole (ACIPHEX) should be aware that it has clinically important interactions with many other prescription medications. Public Citizen’s Health Research Group has designated rabeprazole, a protein pump inhibitor, as Limited Use.
Drug and Food Interactions for the Thyroid Medication Levothyroxine
March 2023
Patients taking the widely prescribed hypothyroidism drug levothyroxine should be aware that it has clinically important interactions with many other prescription and over-the-counter medications, dietary supplements and even certain foods.
Reassuring Findings About Switching Among Generic Versions of the Thyroid Drug Levothyroxine
July 2022
Findings from a new retrospective, real-world observational study that assessed switching among the most common generic levothyroxine products made by different manufacturers in the U.S. suggest that switching among these products is unlikely to have a substantial impact on treatment effects.
Important Drug Interactions for the Stomach-Acid–Suppressing Drugs Lansoprazole and Dexlansoprazole
October 2021
Patients taking the commonly used stomach-acid–suppressing drugs lansoprazole (PREVACID, PREVACID 24 HR) and dexlansoprazole (DEXILANT) should be aware that these drugs have clinically important interactions with many other prescription medications.
Drug-Induced Hair Loss
October 2021
Learn about some of the commonly used medications that may lead to hair loss, also known as alopecia.
Levothyroxine Ineffective for Depressive Symptoms in Elderly Patients With Subclinical Underactive Thyroid
September 2021
In this article, we discuss the results of a recent rigorously conducted study showing that therapy with the thyroid-hormone drug levothyroxine in older adults with subclinical hypo-thyroidism (a mild form of underactive thyroid) who had depressive symptoms provided no significant benefit.
An Update on Drug-Induced Parkinsonism
October 2019
Next to Parkinson’s disease, drug-induced parkinsonism is the second most common cause of parkinsonism, accounting for about 8-12% of all parkinsonism cases. Find out which commonly used drugs can cause this condition.
Drug-Induced Tremor
July 2018
Tremor is the single most common movement disorder, affecting millions of people in the U.S. If you have tremors, could one of your drugs be the cause? Read this article to learn the answer.
FDA: Drug for Treating High Blood Potassium Levels Should Not Be Combined with Other Medications
March 2018
Last year, the FDA warned that a drug used to treat high blood potassium levels can interfere with the absorption of many other oral medications. Learn the name of this drug and how to take it safely when using other drugs.
Endocrine Society Recommends Against Routine Use of Compounded Hormones
December 2016
In this article, we explain why FDA-approved bioidentical hormone medications are preferred over custom-mixed (compounded) products for treating hormone-related disorders.
Oral Treatments for Hypothyroidism
November 2016
Not all thyroid hormone replacement medications are the same, and some are not even approved for use in the U.S. Learn which of these medications you should take — and which ones you should not take — to treat hypothyroidism (underactive thyroid).
Drug-Induced Hair Loss
July 2016
For most people with hair loss, the condition usually is age-related or due to the genes they inherited from their parents. But for some patients, the cause of the problem can be found in the medicine cabinet. Learn about some commonly used medications that can cause hair loss.
Questions & Answers for August 2015
August 2015
A reader asks whether a recent change in her thyroid disorder symptoms could have been caused by switching from a brand name to generic thyroid hormone replacement drug. See our advice regarding concerns about such thyroid medication changes.
Too Much Levothyroxine Increases the Risk of Fractures in Older Adults
August 2011
Many of the millions of older adults who take thyroid pills are taking too much each day, with significantly increased risks of bone fractures. Find out what to do.
Drug-Induced Parkinsonism
October 2010
A study discovered that more than 1 out of every 10 people who went to a Parkinson’s disease center was found to have drug-induced Parkinsonism. These people were misdiagnosed as having the more common illness, Parkinson’s disease, which is irreversible and has unknown causes.
Hypothyroidism: A Consumer’s Guide to Diagnosing and Treatment
June 2009
The article explains why it is not a good idea to start treatment with thyroid hormone replacement without confirmation with laboratory tests that you actually have hypothyroidism. It also discusses the kinds of symptoms that should lead you to have your thyroid level checked.
Do Not Use! Natural or Desiccated Thyroid (ARMOUR THYROID) For Thyroid Hormone Replacement Therapy
May 2003
We wrote in the first edition of Worst Pills, Best Pills, published in 1988, that natural or desiccated (dried) thyroid extract products, such as ARMOUR THYROID, should not be used except by those who have successfully taken it for years to control their symptoms of low thyroid hormone production (hypothyroidism).


Search results below include Additional Information from Public Citizen where your selected drug is a primary subject of discussion.

Testimony before FDA Public Meeting on Levothyroxine Sodium Therapeutic Equivalence (HRG Publication #1744)
This hearing is simply the latest round in a decades-long debate in which discredited scientific arguments are repeated and uncorroborated clinical anecdotes recycled in an effort to generate enough confusion to maintain the market share of the brand name medication, Synthroid, and, to a lesser extent, Levoxyl.
Letter to FDA Commissioner David Kessler Urging Him to Begin a Safety and Efficacy Review of All Pharmaceuticals Marketed in the US Prior to 1938 (including Synthroid) (HRG Publication #1393)
In 1978, the last year for which data are available, the FDA estimated that 240 pre-1938 pharmaceuticals were being manufactured. Of these, only 45 had submitted safety and efficacy data in New Drug Applications, in most instances not for all dosage forms of the medication.