Skip to main content

Potassium iodide Side Effects

Medically reviewed by Last updated on Jul 3, 2023.

Applies to potassium iodide: oral solution, oral tablet.

Serious side effects of Potassium iodide

Along with its needed effects, potassium iodide 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 as soon as possible if any of the following side effects occur while taking potassium iodide:

Less common

  • Hives
  • joint pain
  • swelling of arms, face, legs, lips, tongue, and/or throat
  • swelling of lymph glands

With long-term use

  • Burning of mouth or throat
  • confusion
  • headache (severe)
  • increased watering of mouth
  • irregular heartbeat
  • metallic taste
  • numbness, tingling, pain or weakness in hands or feet
  • soreness of teeth and gums
  • sores on skin
  • symptoms of head cold
  • unusual tiredness
  • weakness or heaviness of legs

Other side effects of Potassium iodide

Some side effects of potassium iodide may occur that usually do not need medical attention. These side effects may go away during treatment as your body adjusts to the medicine. Also, your health care professional may be able to tell you about ways to prevent or reduce some of these side effects.

Check with your health care professional if any of the following side effects continue or are bothersome or if you have any questions about them:

Less common

For Healthcare Professionals

Applies to potassium iodide: compounding powder, oral liquid, oral solution, oral tablet.


The most frequently reported adverse reactions have included stomach upset, diarrhea, nausea, vomiting, skin rash, and salivary gland swelling or tenderness.[Ref]


Hypersensitivity reactions such as skin rashes, swollen salivary glands, headache, bronchospasm and gastrointestinal disturbances can be mild or severe and may be dose dependent.

Frequency not reported: Hypersensitivity


Hyperthyroidism, iodine induced autoimmunity (Grave's and Hashimoto type), toxic nodular goitre and iodine-induced hypothyroidism have been reported as side effects of iodine therapy.

Frequency not reported: Hyperthyroidism, iodine induced autoimmunity (Grave's and Hashimoto type), toxic nodular goiter, iodine-induced hypothyroidism, overactive thyroid gland, thyroiditis, enlarged thyroid gland with or without development or myxoedema


Frequency not reported: Stomach upset, diarrhea, nausea, vomiting, stomach pain, gastrointestinal bleeding, salivary gland swelling or tenderness


Frequency not reported: Skin rash


Frequency not reported: Pain or weakness in hands or feet, weakness or heaviness of legs


Frequency not reported: Unusual tiredness, fever, iodism (chronic iodine poisoning)

Nervous system

Frequency not reported: Confusion, numbness, tingling


Frequency not reported: Irregular heartbeat


1. Cerner Multum, Inc. UK Summary of Product Characteristics.

2. Product Information. iOSAT (potassium iodide). Anbex Inc. 2019.

Further information

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.

Some side effects may not be reported. You may report them to the FDA.