Q: My eight-year-old daughter had a strep infection in a cut on her finger. For this, she was prescribed Amoxil by her doctor. She finished the course of antibiotics and the infection has cleared up.
However, a day later she got a rash on her thighs and on the soles of her feet. Does this mean that she is allergic to penicillin? I have heard of other people getting a rash from penicillin just after finishing the prescription.
A: It has always been a problem when someone develops a rash after or during a course of penicillin treatment.
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Amoxil or Amoxicillin is a type of commonly prescribed penicillin. Sometimes the rash is due to a true allergy to the drug, but often it is part of the original illness. Various bacterial and viral infections may also cause a rash.
I cannot be sure without a physical examination, but it is possible your daughter may have had an atypical case of scarlet fever, which is caused by the streptococcus bacterium.
It usually starts with a sore throat or ear infection, but in rare cases it can begin with a skin infection such as impetigo. One of the major symptoms is a bright red “strawberry” tongue.
These days, scarlet fever is a mild illness, and because your child was given antibiotics, she would have stopped being infectious in a couple of days. However, if you or others in contact with her get a sore throat in the next week or so, you should see your doctor and receive appropriate treatment and tests.
When there is only a vague suggestion that a person has a penicillin allergy, it is important to determine if they really do have it. Otherwise, they are sentenced to using powerful broad spectrum drugs every time they need an antibiotic for the rest of their lives. A skin test is available.
Recent studies have also suggested that penicillin sensitivity may decrease over time. Only one-third of patients who had a vague history of allergy, such as a skin rash or gastrointestinal symptoms, actually tested positive.
Cold cure
David Proud of the University of Calgary’s physiology and biophysics department has been studying the effect of the rhinovirus that causes the cold on the genes of volunteers.
He and his colleagues found that the characteristic effects of a cold are not brought about directly by the virus but by its ability to turn the body’s own defences against itself.
The test subjects who had a cold caused by the rhinovirus were found to have changes in as many as 6,500 of their genes. Some of these genes cause the inflammatory response, while others make an antiviral protein.
Up to half of common colds are caused by various strains of the human rhinovirus.
This research has shown that the infection triggers a domino effect, whereby the body’s own defences over-react, causing the familiar symptoms of sneezing, runny nose and coughing.
“The response seems to be out of proportion to the threat posed to the cold,” the scientists said.
The genes that had been altered by the virus included those that make anti-viral proteins that fight the infection and also those involved in inflammation, which would cause the stuffy blocked nose feeling and cause a runny nose.
The protein is known as viperin and it seems to block the rhinovirus’s ability to grow and multiply.
Treatments for colds so far have focused only on alieviating symptoms rather than any actual cure.
The Calgary study was carried out in collaboration with scientists at the University of Virginia and Procter & Gamble, which makes over-the-counter cold treatments.
Clare Rowson is a retired medical doctor living near Belleville, Ont. Her columns are intended for general information only. Individuals are encouraged to also seek the advice of their own doctor. She can be reached at health@producer.com.
