Healthy Living

Signs You Have a Penicillin Allergy

Signs You Have a Penicillin Allergy

What is Penicillin?

Penicillin is known to be one of the most commonly used antibiotics that is often prescribed by doctors. Penicillin belongs to the family of antibiotics that is known as beta-lactams.

What is a Penicillin Allergy?

A penicillin allergy would usually occur to an individual when the body’s immune system tends to overreact to penicillin antibiotics. Penicillin is a drug that is used to treat various types of infections caused by bacteria. Penicillin allergy is a problem that can result in usage of less appropriate and more expensive types of antibiotic treatments. Hence, one should carry out an accurate diagnosis if he suspects an allergy caused by this antibiotic, so that he can ensure that the best treatment options are taken in future.

The common symptoms that an individual would experience pertaining to a penicillin allergy are hives, itching, and rashes on the skin. A severe form of reaction would be anaphylaxis, which can tend to impact multiple body functions. Apart from penicillin, there can be other drugs that can cause allergic reactions in certain individuals.

When it comes to drug allergies, penicillin is one of the most common drug allergens. Also, it is said that those individuals who have been allergic to penicillin would also be allergic to other kinds of medications that are closely related to penicillin. Those medications would include cefuroxime, cephalexin, and cefprozil. All these drugs belong to the category cephalosporins. Hence, it is always better to verify with the doctor before starting any medication and worsening the existing condition.

In many cases, individuals feel they have an allergy to penicillin, but it is not truly an allergy. Those individuals would be less sensitive toward penicillin as was the case in the past, or it could be an adverse reaction such as a side effect instead of a penicillin allergy. The best way to confirm whether it is an allergy or not is to conduct a skin test under the guidance of a dermatologist or allergist.

Symptoms of Allergies

The various signs an individual would encounter after the exposure to penicillin are mentioned below. If not all, a few of these symptoms can appear, and the reaction would occur within an hour after taking the medication. Reactions that rarely occur can take place after hours or even days and weeks after the exposure to the drug.

The symptoms of a drug allergy would include:

  • Irregular breathing or shortness of breath
  • Rashes appearing on the skin
  • Hives
  • Watery or itchy eyes
  • Fever
  • Runny nose
  • Swelling and itching of the skin
  • Wheezy breathing
  • Anaphylaxis
  • Swelling of the face, lips, and/or tongue
  • Loss of consciousness
  • Pulse range that becomes weak and sometimes fast
  • Nausea
  • Color of the skin turning bluish
  • Vomiting
  • Diarrhea

Anaphylaxis: This condition is one of the common symptoms seen in most allergic reactions. It is quite rare, but it can also be severe and life-threatening. Anaphylaxis can lead to a widespread dysfunction of the systems in the body. Below are the signs that point towards anaphylaxis:

  • Sudden drop in the blood pressure
  • Feeling lightheaded
  • Diarrhea
  • Vomiting
  • Having trouble while breathing due to tightness in the airway passage and the throat
  • Cramps in the abdomen
  • Seizure attacks
  • Rapid pulse rate
  • Nausea
  • Loss of consciousness

While serious, one is not likely to have an anaphylactic reaction when they have a penicillin allergy. The individual would experience a rash that looks quite similar to measles. This rash would have developed after a couple of hours or days after the intake of penicillin.

Rashes caused by penicillin: There are various or several types of rashes that can appear in an individual who is allergic to penicillin.

  • Firstly, there can be rashes with hives. It is basically a rash which is raised and leads to intense itching that tends to come and go, over and over again. This itching can happen on any part of the body.
  • The second type of rash would be the ones that look flat and blotchy. These rashes spread over the days and do not change frequently. In some cases, it can reflect a dangerous allergy. Mostly, these rashes would occur after several days of starting the treatment with penicillin.

A penicillin allergy can also lead to other medical conditions that can tend to get serious. These are less common signs of the allergy and can usually occur mostly hours or days, and sometimes weeks, post exposure to the drug. These reactions can stay for a while after you stop taking the medicine. These conditions include:

  • Kidney inflammation: This condition is also known as nephritis, and it can lead to symptoms such as fever, swelling that is generalized, having traces of blood in the urine, signs of confusion, and other symptoms.
  • Serum sickness: This type of condition can lead to symptoms such as swelling, nausea, pain in the joints and muscles, fever, and skin rashes.
  • Drug reaction with eosinophilia and systemic symptoms: This condition is also abbreviated as DRESS, and it leads to symptoms such as swelling in the lymph nodes, increase in the count of white blood cells, skin rashes, swelling that is generalized, and there can also be a recurrence of the hepatitis infection that was dormant all the while.
  • Drug-induced anemia: This condition can lead to symptoms such as a decrease in the count of red blood cells, leading to tiredness, fatigue, heartbeats which are fast and at times irregular, irregular breathing, and many other symptoms.

Causes of Allergies

An individual becomes allergic to penicillin when the body’s immune system erroneously reacts to the medicine and treats it as a substance that could cause potential harm to the body. It treats it as a virus or bacteria. This usually occurs when the immune system is over-sensitive towards penicillin and any of its related drugs.

Thus, it means that the very first time the individual consumed the drug, the immune system detected it as a harmful substance and released antibodies to the type of penicillin one consumed. Hence, the next time one consumes penicillin, these specific antibodies flag it as a red sign and direct the body’s immune system to attack the substance. Any chemicals that get released in this process of attack leads to the signs and symptoms one experiences during the allergy.

Penicillin belongs to the class of drugs that are antibacterial and are called beta-lactams. The medications that fall under this class of drugs are known to ward off any infections by attacking the walls of the bacterial cells. Apart from penicillin, there is another class of beta-lactams, which are commonly known to cause allergic reactions and are termed cephalosporins. If an individual is suffering from one type of penicillin allergy, then it is not necessary, but they can also be allergic to the other types of penicillin drugs or any drug that falls under the group cephalosporins.

Penicillin-related drugs would include Ticarcillin, Ampicillin, Oxacillin, Penicillin G, Dicloxacillin, Amoxicillin, Penicillin V, and Piperacillin.

Medications under the group Cephaslosphorins would include Cefdinir, Cefaclor, Cefazolin, Cephalexin, Cefadroxil, Cefotetan, Cefuroxime, and Cefprozil.

Risk Factors of Allergies

Allergy to penicillin is quite common, but there are certain factors that one needs to understand, since they can increase the risk of getting the allergy:

  • An existing reaction to another type of drug
  • Past history of allergy to different substances, such as hay fever or an allergy to food
  • An individual who has an increased exposure to penicillin due to higher dosages and longer duration of using them
  • There can be instances of illnesses that are commonly associated with allergic drug reactions, such as Epstein Barr Virus or HIV

Visit to the Doctor

It is very important to visit the doctor if one experiences any symptoms that may indicate an allergic reaction to the penicillin drug or any other antibiotic that has been started recently. The doctor would ask you certain questions that you would need to be prepared to answer so that it becomes easier for diagnosis, as well as for determining the cause which is leading to the symptoms. The doctor may ask the below questions:

  • What is the name of the penicillin drug being taken or any other antibiotic which has been started recently?
  • What are the various symptoms being experienced, and when did the symptoms start to appear?
  • After taking the medicine, how long did it take for the symptoms to start appearing?
  • What was the reason for being prescribed this medicine?
  • Did these symptoms also appear in the past when this drug was not being taken?
  • What was the duration of the symptoms, or how long did they last once they appeared?
  • Is your treatment now on halt, or are you still taking the medicine?
  • Apart from penicillin, what are the other drugs being taken, such as over-the-counter or prescription drugs?
  • Are you also taking any supplements, vitamins, or herbal or dietary products?
  • Were any of the medicine dosages increased, including penicillin?
  • What are the other allergies you suffer from, apart from the drug allergy?
  • Did you face any other drug reactions in the past, and if yes, then what was the drug?
  • Is anyone in your family allergic to any substance, including but not limited to drug allergies?


To get an accurate diagnosis, it is very important to conduct a thorough examination and appropriate level of diagnostic testing. Studies reveal that in certain cases, the allergies due to penicillin tend to get overdiagnosed, and the patient is likely to report an allergy which has not been confirmed yet.

The doctor would first go for a physical examination and ask certain questions about the symptoms and the allergy. After the physical examination and the questioning session, the doctor would ask for certain tests to be carried out and can refer the case to an allergy specialist. Diagnostic tests may include the following.

  • Skin tests: To conduct the skin test, the nurse or the doctor would administer a small amount of suspect penicillin to the skin with the help of a needle, which would scratch the skin, or with the help of an injection. The positive reaction to this skin test would lead to signs of a raised bump that is red and itchy. This positive result would confirm the presence of a penicillin allergy, whereas if the test is negative, it would mean that person is not allergic to penicillin. However, it is very difficult to interpret the negative results, since there are some kinds of drugs whose reactions are not easily detected via a skin test.
  • Graded challenge test: To conduct the graded challenge test, the individual would receive around four to five doses of the suspected penicillin. The dose would start with a small quantity, and gradually, it would be increased to the desired dose. If the dose is reached to a therapeutic level with no signs of reaction, then it is confirmed that the individual is not allergic to that type of penicillin drug. Hence, the doctor would ask you to continue the prescribed dose and medicine. While conducting this graded challenge test, the doctor would ensure to carry out proper supervision, along with supportive care for an adverse reaction to the medicine.

Treatment of Allergies

The following methods can be used to treat the symptoms pertaining to the drug reaction:

  • Stopping the use of the drug: If the doctor has confirmed that the allergic symptoms are due to the penicillin drug, then he would ask for an immediate discontinuation of the medicine as part of the first treatment plan.
  • Antihistamines: The doctor can also prescribe certain antihistamines or over-the-counter antihistamines, such as Benadryl, which would help to block the chemicals that get activated by the immune system in defense of any foreign unwanted substance.
  • Corticosteroids: Oral or injected forms of corticosteroids can be used for providing relief from the inflammation that is usually associated with the serious reactions.