Antibiotics: Knowing the Side Effects by Your Marque Medical Team

When infections get worse, antibiotics usually are the solution, but in some cases, antibiotics can only do so much. For instance, a viral infection such as influenza or chickenpox, is mostly repellent to medication, and has to go its course.

If the doctor determines that the condition is bacterial (not viral), it is important to understand that antibiotics are not an instant cure to the illness. Most of them have to work into your immune system for a few hours to a few days since each person’s immunity is different.  Once you start taking the medication, it is necessary to finish the entire prescription even when symptoms are improving.

Sometimes, just when everything seems to be going right, there can be a sudden turn because side effects are a possibility when taking antibiotics. Some of the most common effects can grow from moderate to severe. It is crucial to know these effects in the event of an allergic reaction or anaphylaxis, which is a more serious reaction.

The most commonly used antibiotics and their mild allergic reactions are:


Rash, diarrhea, abdominal pain, nausea, vomiting, fever, and sometimes in cases can cause vaginal candidiasis (yeast infection).

Amoxicillin/Clavulanate Potassium  (Augmentin)

Rash, diarrhea, abdominal pain, nausea, vomiting, and/or fever.

Cephalexin (Keflex)

Rash, diarrhea, nausea and/or vomiting (rare), hypersensitivity (allergic) reactions ex: serum sickness and sometimes vaginal candidiasis (yeast infection).

Ciprofloxacin (Cipro)

Nausea and/or vomiting, diarrhea, abdominal pain, headache, lethargy, insomnia, muscle pain and sometimes photosensitivity to sunlight.

Azithromycin (Zithromycin or  Z-pack)

Abdominal pain, diarrhea, nausea and/or vomiting, and sometimes taste alterations.

One may experience a single side effect or all of them. If the effects are mild, they usually last a few hours. These issues can sometimes be treated with home remedies or OTC medications.  If side effects worsen and are continuous to the next few days, then it is advisable to consult with a doctor.

Severe Allergic Reactions that can be Anaphylactic:

Any of the following reactions: shortness of breath, harsh wheezing, intense abdominal pain or rash, swelling of the face, throat or tongue and fever of 102 and above, can be considered a severe reaction and would need attention immediately.  Always note your first instinct and act on it! If it may be anaphylactic and a true emergency, dial 9-1-1 or have someone drive you to the closest ER.

Acknowledging the side effects of not only antibiotics but of any medications is important in order to live healthy. If you have questions about drug interactions, minor or major side effects or allergies, talk with a doctor. Let them know how you feel about taking them and any concerns you may have. They will be able to assist you in finding the right antibiotic or alternatives.

The information provided is for general interest only and should not be misconstrued as a diagnosis, prognosis or treatment recommendation. This information does not in any way constitute the practice of medicine, or any other health care profession. Readers are directed to consult their health care provider regarding their specific health situation. Marque Medical is not liable for any action taken by a reader based upon this information.


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