Penicillin Allergy: Symptoms, Causes, Risks, Diagnosis, Treatment and Prevention

Blue Penicillin Allergy Bracelet and a bottle with pills


Penicillin is an antibiotic that is used to fight bacterial infections like upper respiratory infections and sometimes for wounds. Most doctors prescribe penicillin because it is readily accessible to the public and cost-effective. Allergic reactions to penicillin are not common but hypersensitivity to the antibiotic is seen in many cases like having rashes throughout the body, redness on the skin, nausea and sometimes vomiting. Severe reactions to the drug consist of only 10 percent of the population and require emergency treatment.

Some allergic reactions are often associated with other antibiotic drugs that consist of similar ingredients as penicillin thus people think that they are allergic to penicillin itself. About 90 percent of the population that claims they have an allergy to penicillin tend to be free from the allergy through the course of time, but almost 10 percent of them do not lose this allergy thus requires treatment.


In common cases of penicillin allergy, people demonstrate adverse physical reactions, especially on the skin. This symptom is seen immediately after taking in the medicine like:


Localized or generalized itching is prominent on the upper back, neck, face, and chest. Itchiness is also felt by the patient when suffering from a reaction to the medicine.


When a person is known to have an allergy to penicillin, the immune response will be triggered to get rid of the penicillin causing inflammation to cell and muscle tissues in the process. Angioedema is usually found on the face and neck but in some rare cases, the tongue and lips will also swell.

Difficulty in breathing

Allergies cause difficulty in breathing because the smooth muscles of the throat will swell make the air passage narrow thus resulting to the difficulty in breathing of the person.


Aside from swelling as a result of the inflammatory response, Fever may also occur.
The increase in temperature of the body helps fight the pathogens that enter the system.

A runny nose and watery eyes

People will have symptoms that also affects the eyes and nose as a reaction to the allergen in the body. Sometimes the eyes will appear as red or in medical term, Conjunctivitis.


It is the severe reaction when having an episode of allergy. In these situations, the life of the patient may be in danger and requires immediate treatment. Symptoms like loss of consciousness, weak pulse to the absence of pulse, confusion, and weakness is apparent to this situations.

Immediate reactions are common for people but for some, there is a delayed reaction and can cause problems in the body. It may take days, weeks and even months like:


It is the inflammation of the kidneys that can cause back pain accompanied by fever, blood in the urine and because the kidney is impaired because of the inflammation the water is retained inside the body thus swelling occurs.

Serum Sickness

It is like an allergy that can cause fever and rash along the body and sometimes a person may feel nauseous.

Drug reaction with eosinophilia and systemic symptoms (DRESS)

This is a life-threatening event that involves abnormalities in the blood and severe skin rashes. When this disease is left untreated it can cause a lot of problems involving the different organs in the body like the kidneys and liver.


Anemia happens when there is a low supply of red blood cells in the body. These cells are responsible for carrying oxygen in the different parts of the body. If there are not enough red blood cells in the body, oxygen deprivation will occur in the organs and may result in exhaustion, fatigue, and paleness. Pallor or paleness are commonly seen on the palm of the hands, the conjunctiva of the eyes and mucosa inside the mouth.


When the person first takes a penicillin, the body will detect it and interpret it as a foreign body and makes an antibody that can fight off the antigen and preserve it for future purposes.

When the person again takes in a penicillin, the body will now release the antibodies and fights the drug causing inflammatory response producing some chemicals that are circulated throughout the body and that is where we can see the symptoms.

4Risk Factors

Everyone is at risk of having a penicillin allergy when the person takes frequent penicillin doses, who take high doses of the drug. Some studies say that females also have a higher risk of having a drug allergy like penicillin. The other risk factors are:

Having a family member that has a drug allergy may increase your risk of acquiring the same allergy to the drug or another drug.

If the person has an allergy to food or other substances, it can also trigger other allergies due to the hypersensitivity of the immune system. Medication allergy can also be a factor that can contribute to having a similar reaction when the person takes in penicillin.

Persons who have problems in their immune system have medications that help them have a better quality of life and that can also have a reaction when they take penicillin.


There are several tests to verify if the patients claim that they are allergic to penicillin drug. The doctor will ask questions about the medical history of the patient and also when did they first experience the symptom at hand, is the patient allergic to any food or drugs aside from penicillin.

There are two types of skin test that the doctor can do to determine if the patient has an allergy to the said drug.

Skin prick

The doctor will prick the skin with a sterile needle that contains a serum containing the penicillin. The results like redness on the skin, a rash, pain, and swelling will be seen immediately right after the test.

Intradermal skin test

It requires a sterile needle that also contains the medicine and it is introduced underneath the skin. If the person is not allergic to the drug, there will be no reactions on the same site.

Blood test

This can help determine the serum, immunoglobulin E, that is present when there is an allergic reaction happening.

There is also a method that can also help the doctor determine whether the person is sensitive to the drug. The graded challenge requires a specific dose of the drug in succession until the desired dose is meet.

If the patient did not react to the first dose of the drug, it is again repeated at a slightly higher dose and if there is still no evidence of reaction the dose is increased again until the dose that the doctor prescribed. After all the tests and there are no reactions, the doctor can now tell that the patient is not allergic to penicillin.


Medications can handle and treat the symptoms on hand like:


These are prescribed by the doctor to help lessen the allergy symptoms. The mechanism of action of the drug is that they inhibit the histamines to bind with the receptor sites which are the H1 receptors and H2 receptors are found in the gastric area. When the Histamine binds to a receptor it will cause an allergic reaction, the antihistamines stop this process by binding to the receptors sites instead of the histamine.

The use of the drug will be stopped to prevent further serious reaction like that may result in long-term damage to the body.

Non-steroidal anti-inflammatory drugs or corticosteroids

These drugs can reduce the inflammation in the muscles and cells that can cause damage when it is not managed immediately. The inflammation is caused by the immune system responding to the invaders that entered the body.


Emergency drugs like epinephrine are given to a patient who is having anaphylaxis, a serious complication that is life-threatening to the patient. This drug reduces the inflammation and other symptoms of the reaction.


Desensitization of the drug can help the patient recover from the allergy. It is a series of treatments that require several doses of the controlled drug to be introduced to the patient. The doctor will monitor your condition, if there is no reaction to the drug, the treatment will then continue in a controlled setting.


If you suspect that you are allergic to the drug, go to your physician to have a thorough examination. To the persons who have an allergy to penicillin prevention is better than suffering from the reaction itself.

  • Use a mark to tell others that you have an allergy to penicillin, today we have medical bracelets that can help others determine what they must do in case of emergency.
  • Be transparent to your company and your co-workers that you have a certain allergy. A well-informed significant other could help you when you are in trouble and also can assist you in your activities of daily living.
  • Always carry medications that are prescribed to you like antihistamines and sometimes epinephrine. Before the emergency drug, epinephrine will be given to the patient, there will be a training required on how to use the injectable form of the drug.