Mild stinging may occur. If this effect lasts or gets worse, stop using this product and tell your doctor or pharmacist promptly.
If your doctor has directed you to use this medication, remember that your doctor has judged that the benefit to you is greater than the risk of side effects. Many people using this medication do not have serious side effects.
Though very unlikely, it is possible this medication could be absorbed into your blood. Children using this drug for an extended time over large areas of the skin (especially areas with broken skin) may be at higher risk, especially if they also are using other diphenhydramine products taken by mouth or applied to the skin. Stop using this product and tell the doctor right away if any of the following serious side effects occur: enlarged pupils in the eyes, face flushing, mental/mood changes (such as hallucinations, unusual excitement, confusion), difficulty walking, difficulty urinating.
A very serious allergic reaction to this drug is rare. However, get medical help right away if you notice any symptoms of a serious allergic reaction, including: rash, itching/swelling (especially of the face/tongue/throat), severe dizziness, trouble breathing.
This is not a complete list of possible side effects. If you notice other effects not listed above, contact your doctor or pharmacist.
In the US – Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088 or at www.fda.gov/medwatch.
In Canada – Call your doctor for medical advice about side effects. You may report side effects to Health Canada at 1-866-234-2345.