T78.4: Allergy, unspecified

You have had an allergic reaction to something.

With an allergy, the immune system overreacts to certain substances. Such substances may be harmless substances in the environment, drugs or certain chemicals, for example.

An allergy may be accompanied by a range of symptoms. For example, you may experience sneezing, swellings or changes to your skin. The eyes and skin may feel itchy. When allergic reactions are very severe, you may suffer from breathlessness or circulatory problems.

Additional indicator

On medical documents, the ICD code is often appended by letters that indicate the diagnostic certainty or the affected side of the body.

  • G: Confirmed diagnosis
  • V: Tentative diagnosis
  • Z: Condition after
  • A: Excluded diagnosis
  • L: Left
  • R: Right
  • B: Both sides

Further information


This information is not intended for self-diagnosis and does not replace professional medical advice from a doctor. If you find an ICD code on a personal medical document, please also note the additional indicator used for diagnostic confidence.
Your doctor will assist you with any health-related questions and explain the ICD diagnosis code to you in a direct consultation if necessary.


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