True allergy or other symptom?
By guest blogger Michael Cohen:
When patients know they are allergic to a medication, most often they’ll tell their doctors and pharmacists about it so that drug won’t be prescribed. All too often though, the patient doesn’t include the type of reaction they experienced and their health professionals don’t always ask. This could lead to unnecessarily withholding an important medication. Very often the patient has actually experienced a non-life-threatening drug reaction such as stomach upset or rash, which could actually even be a side effect of another drug the patient is taking or a disease symptom, but not a true allergy.
Recently, a doctor wrote to us to point out such
a problem, often seen when “codeine” is listed as an
“allergy” on patient records. When patients are
asked about their “allergy” symptoms, many will
state that the drug makes them drowsy or nauseated,
which clearly is not an allergy. Sometimes the
“allergy” can then mislead practitioners and cause
modification of treatment decisions unnecessarily.
On occasion that not only prevents the primary
treatment, it has also led to other complications.
In one reported case, an elderly debilitated patient
was admitted to the hospital for an elective hernia
repair. The patient was very thin with recent loss
of weight and muscle mass caused by his disease. He
had been taking a drug called Tegretol every day for
many years for a seizure disorder. In the patient’s
chart was a notation that he was “allergic” to
codeine, when it really just made him sleepy.
Because of this, the surgeon deviated from
prescribing codeine, which he normally did after a
hernia operation. Instead he ordered Darvocet to be
continued after discharge.
The next day, the patient took one dose of
Darvocet-N for pain but did not feel well. The
following day, he was found dead in his home, which
a coroner attributed to carbamazepine poisoning. The
patient’s carbamazepine level, which had always been
maintained at normal levels, was nearly 4 times
higher than normal. This was caused by a drug-drug
interaction between Darvocet and Tegretol. Darvocet
can decrease the breakdown and excretion of
Tegretol, thereby increasing blood levels of the
drug, causing toxicity.
No one knows for sure what the surgeon would have
prescribed had the patient’s chart reflected that
codeine made him sleepy. However, the
mischaracterization of the “allergy” clearly led the
physician to prescribe a different medication than
his usual codeine, which then led to the adverse
drug event.
Patients and health professionals need to
communicate the symptoms any patient experiences
with a problem drug. Details on a reaction to
penicillin, for example, can help distinguish
classic allergy symptoms such as anaphylactic shock
or swelling of tongue or throat, from a non-allergic
reaction such as GI symptoms. One of the penicillin
antibiotics is often the drug of choice for certain
infections, so avoiding its use for easy-to-treat
side effects would be inappropriate. Yet about
85-90% of patients who say they’re “allergic” to it
do not react when penicillin allergy testing is
done.
Although not every hospital keeps track of symptoms that led the patient to report an “allergy,” we have seen computer systems in hospitals that require the name of the drug (or category) to be chosen from a pull-down list that is correlated with another pull-down list to document the related symptom.
Make sure to keep your health professionals aware of allergies and side effects. It’s certainly to your benefit.
For information on the Institute for Safe
Medication Practices' consumer website go
www.consumermedsafety.org
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www.philly.com/checkup.