Antithyroid Agents (Systemic)

Side Effects of This Medicine

Along with its needed effects, a medicine may cause some unwanted effects. Although not all of these side effects may occur, if they do occur they may need medical attention.

Check with your doctor immediately if any of the following side effects occur:

Less common

Cough; fever or chills (continuing or severe); general feeling of discomfort, illness or weakness; hoarseness; mouth sores; pain, swelling, or redness in joints; throat infection

Rare

Yellow eyes or skin

Check with your doctor as soon as possible if any of the following side effects occur:

More common

Fever (mild and temporary); skin rash or itching

Rare

Backache; black, tarry stools; blood in urine or stools; shortness of breath; increase in bleeding or bruising; increase or decrease in urination; numbness or tingling of fingers, toes, or face; pinpoint red spots on skin; swelling of feet or lower legs; swollen lymph nodes; swollen salivary glands

Symptoms of overdose

Changes in menstrual periods; coldness; constipation; dry, puffy skin; headache; listlessness or sleepiness; muscle aches; swelling in the front of the neck; unusual tiredness or weakness; weight gain (unusual)

Other side effects may occur that usually do not need medical attention. These side effects may go away during treatment as your body adjusts to the medicine. However, check with your doctor if any of the following side effects continue or are bothersome:

Less common

Dizziness; loss of taste (for methimazole); nausea; stomach pain; vomiting

Other side effects not listed above may also occur in some patients. If you notice any other effects, check with your doctor.