Documenting Drug Allergies and Drug Intolerance

Documenting Drug Allergies and Drug Intolerance

Promote coding specificity and improved quality of care.

It’s extremely important to teach patients the difference between true allergic reactions to drugs and anticipated adverse effects to drugs because treatment decisions could be affected. When patients are able to accurately describe their symptoms, physicians are better equipped to improve health outcomes and generate quality data through accurate diagnosis coding.

Drug Allergy vs. Intolerance

An allergic reaction occurs when the immune system overreacts to a harmless substance, such as a drug, which triggers an allergic response. Intolerances to drugs may produce similar symptoms, but do not involve the immune system.
For example: A patient may indicate that he is “allergic to penicillin” because he experiences diarrhea when taking penicillin. A patient may say she is “allergic to aspirin” because taking aspirin gives her heartburn. A patient may claim to be “allergic to cough syrup with codeine” because he experiences constipation and drowsiness when taking opium-derived medications. Such adverse effects are drug intolerances, rather than allergic reactions.
Symptoms of allergic drug reactions may include:

  • Constriction of the airways and wheezing or breathing difficulties, tightness in chest
  • Fainting, dizziness, confusion, or weakness
  • Fall in blood pressure, sometimes to dangerously low levels
  • Fever
  • Hives, rashes, and itching
  • Swelling of tissues (in the face, tongue, lips and/or throat), which can impact breathing and swallowing
  • Tachycardia
  • Weak pulse, paleness
  • Vomiting

When coding an adverse effect for a drug that was correctly prescribed and properly administered:

  1. Code for the side effect of the drug (e.g., diarrhea);
  2. Code for the adverse effect of the drug; and then
  3. Code the underlying treated condition that necessitates the drug.

Adverse Effect Example

Here’s an example of an adverse effect from a properly prescribed and properly administered drug and how to code:
Initial encounter for opioid-induced constipation due to hydrocodone the patient takes for chronic pain. Chronic pain caused by lumbosacral spinal stenosis and intervertebral disc disorders in the thoracic region with radiculopathy, which were diagnosed four years ago.
K59.03          Drug induced constipation
T40.2X5A     Adverse effect of other opioids, initial encounter
M48.07         Spinal stenosis, lumbosacral region
M51.14          Intervertebral disc disorders with radiculopathy, thoracic region
G89.29         Other chronic pain

Allergic Reaction Example

Here’s an example of an allergic reaction to medication:
Initial encounter for a patient who went into anaphylactic shock after taking properly prescribed and properly administered penicillin for cellulitis of the buttock.
T88.6XXA     Anaphylactic reaction due to adverse effect of correct drug or medicament properly administered, initial encounter
T36.0X5A     Adverse effect of penicillins, initial encounter
L03.317         Cellulitis of buttock

Documentation Must Be Specific

If you’re in a position to educate your service providers or clinical staff, ask them to be specific about the drug reaction the patient experienced, and to document which drug caused the reaction. This will help differentiate between a patient with a true drug allergy and a patient with a drug intolerance. This documentation may also help support a higher level of medical decision-making for an evaluation and management service, aid the service provider in choosing an alternate medication, and promote quality patient care.


Here are two good articles relating to drug allergies and adverse effects:
Merck Manual Consumer Version. Smith Marsh, Daphne. “Allergies to Drugs:”
American Pharmacists Association. “Allergy or Adverse Effect: Teach Patients the Difference,” March 1, 2014:

Maryann Palmeter

About Has 23 Posts

Maryann C. Palmeter, CPC, CPCO, CPMA, CENTC, CHC, has more than 30 years of technical and executive level experience gained through her work on both the government payer and professional billing ends of the healthcare spectrum. She is director of physician billing compliance at the University of Florida Jacksonville Physicians, Inc., and is responsible for providing professional direction and oversight to the billing compliance program of the University of Florida College of MedicineJacksonville. Palmeter served on the AAPC’s National Advisory Board from 2011-2013 and was subsequently selected to serve as secretary for the 2013-2015 term. She was named the AAPC’s 2010 “Member of the Year” and is the vice president for the Jacksonville, Fla., local chapter.

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