Unithroid vs. Synthroid for Thyroid Cancer and Hypothyroidism: Important Differences and Potential Risks.

Unithroid

(levothyroxine)

Synthroid

(levothyroxine)

Summary for Unithroid

Prescription only

Unithroid (levothyroxine) is a thyroid hormone used to treat hypothyroidism, or low thyroid hormone levels, in people of all ages. It's also used to treat a certain type of thyroid cancer. The medication comes as a tablet that you take once a day by mouth, typically on an empty stomach in the morning. Regular blood tests are needed to keep your dose in the right range. Common side effects usually happen when the dose is too high and can include fast heartbeat, headache, trouble sleeping, or weight loss.

Indications for Unithroid

Hypothyroidism (low thyroid hormone levels)
Thyroid cancer, together with radioactive iodine and surgery

Pros and Cons for Unithroid

Pros

First-choice medication for treating low thyroid hormone levels
Safe to use during pregnancy
Only needs to be taken once a day
Can be taken by both children and adults

Cons

Must be taken on an empty stomach
Might take several weeks to find the right dose
Requires regular blood tests
Interacts with many foods, medications, and supplements

Common Side Effects for Unithroid

Signs of having too much thyroid hormones in the body, such as:

Irregular heartbeat
Chest pain
Shortness of breath
Leg cramps
Headache
Nervousness
Hives or skin rash
Irritability
Trouble sleeping
Tremors
Muscle weakness
Change in appetite
Weight loss
Vomiting
Diarrhea
Sweating a lot
Sensitivity to heat
Fever
Changes in menstrual period

Warnings for Unithroid

Not for weight loss
Heart problems
Adrenal crisis in people with adrenal insufficiency
Worsening diabetes
Bone loss

Summary for Synthroid

Prescription only

Synthroid (levothyroxine) is a thyroid hormone used to treat low thyroid hormone levels (hypothyroidism) in both children and adults. It's also used to treat a certain type of thyroid cancer. The medication comes as tablets in many different strengths. It's taken once a day by mouth, usually on an empty stomach in the morning. You'll need regular blood tests to make sure you're getting the right dose. Side effects can include headache, trouble sleeping, and weight loss.