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Dr. Abby
Dr. Abby, Board Certified MD
Category: Health
Satisfied Customers: 10330
Experience:  Family Physician, practicing medicine for over 10 years, United States
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how long does does a one time injection of penicillin stay

Resolved Question:

how long does does a one time injection of penicillin stay in the system
Submitted: 6 years ago.
Category: Health
Expert:  Dr. Abby replied 6 years ago.
Hello,

What was the penicillin given for?

Dr abby
Customer: replied 6 years ago.
My 5 year old daughter was diagnosed with strep throat. They gave her a penicillin shot, I was wondering how long it will be in her system since she has been having mild rashes on and off the shot was given 4 days ago
Expert:  Dr. Abby replied 6 years ago.
Thank you for clarifying,

I am sorry she is having the rash.

It is difficult to say exactly how long the penicillin will stay in her system as it is dose dependent...but for a dose given for strep throat, it will be in her system for approximately one week.

If she is otherwise healthy, you can treat the rash with benadryl or zyrtec (if the rash is bothering her). While zyrtec can also make children drowsy, it may be less sedating than benadryl for her.

Feel free to ask any follow up questions,

Dr Abby

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Customer: replied 6 years ago.
thank you for your response, one more question please. Can the symptoms get worse. Or is this as far as her allergic reaction will go?
Expert:  Dr. Abby replied 6 years ago.
She should not develop an anaphylactic response at this point (4 days out), no--anaphylaxis being throat closing up, tongue swelling, difficulty breathing.

Her rash could worsen on and off. But she should not develop a life threatening reaction.

In the future, she could develop a more severe reaction to penicillin if she is given it again. So she should not receive penicillin again.

Dr Abby

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Customer: replied 6 years ago.
Thank you sooooo much. I have been very worried things could get worse. The rashes are not bothersome to her right now. They just kind of come and go. I appreciate my mind being put at ease.
Expert:  Dr. Abby replied 6 years ago.
You are very welcome!!

Enjoy your weekend and take care,

Dr abby