• Facebook
  • Instagram
MAKE YOUR APPOINTMENT: 617.472.7111
Vallen Allergy & Asthma
  • Home
  • About
    • What To Expect
    • List of Antihistamines
    • Educational Links
  • Our Providers
  • New Patient Information
    • Request An Appointment
    • Insurance Information
    • Medical Record Release
    • School Medication Form
    • What to bring to your appointment
  • Conditions
    • General Allergy Info
    • Drug Allergies
    • Asthma
    • Bee Sting Treatment
    • Food Allergies
    • Eczema/Atopic Dermatitis
    • Chronic Sinusitis
    • Chronic Hives
    • Patch Testing
  • News
  • Contact
  • Menu Menu
Penicillin Allergy: What You Need to Know Before Avoiding Antibiotics

Penicillin Allergy: What You Need to Know Before Avoiding Antibiotics

January 15, 2026/in News

Penicillin Allergy: What You Need to Know Before Avoiding Antibiotics

 

Many people worry they are “allergic” to penicillin, but most who carry that label are not truly allergic and can actually take penicillin safely after proper evaluation. Understanding what a real penicillin allergy is, how to get tested, and when to avoid penicillin can help you and your clinician choose the safest and most effective antibiotics.

How common is penicillin allergy, really?

  • About 10% of people in the United States say they have a penicillin allergy.
  • When those patients are formally evaluated, fewer than 1% of the total population are found to be truly allergic.
  • Studies show that 80% to 90% of people once labeled penicillin‑allergic can ultimately tolerate penicillin again, especially if many years have passed.

In practice, this means many penicillin “allergies” are inaccurate labels, often based on childhood rashes, side effects like stomach upset, or vague memories of a reaction. Losing this label when it is not accurate is important because it opens the door to better, narrower‑spectrum antibiotics and fewer complications.

Why does the label matter?

Carrying a penicillin allergy label affects more than just one prescription.

  • You are more likely to receive broad‑spectrum antibiotics like fluoroquinolones, clindamycin, or vancomycin instead of first‑line penicillins.
  • Use of these broader drugs is linked with higher rates of C. difficile infection, MRSA, and VRE, as well as more drug side effects.
  • People with a penicillin allergy label may have longer hospital stays, more surgical site infections, and higher healthcare costs.

Because of these risks, allergy and infectious disease experts now strongly encourage proactively evaluating penicillin allergy labels rather than avoiding penicillin for life.

Example

A patient labeled “penicillin‑allergic” as a child for a mild rash later needs surgery. Instead of a standard penicillin‑type antibiotic, they receive a broader drug and end up with C. difficile diarrhea, a complication that might have been avoidable if their label had been checked and removed.

What does a true penicillin allergy look like?

A true penicillin allergy is an abnormal immune reaction to the drug, and it can be immediate (within minutes to hours) or delayed (days later).

Immediate (IgE‑mediated) reactions

These usually occur within an hour but can show up within the same day of a dose. Common features include:

  • Hives (raised, itchy welts)
  • Swelling of lips, tongue, face, or throat
  • Trouble breathing, wheezing, chest tightness
  • Dizziness, fainting, low blood pressure
  • Anaphylaxis, which is a life‑threatening whole‑body allergic reaction

Immediate allergic reactions are serious and require urgent care; patients with this pattern should avoid penicillin until evaluated by an allergy specialist.

Delayed reactions

Delayed reactions show up days after starting penicillin and can range from mild to life‑threatening.

  • Mild: flat red rash, sometimes itchy, without other symptoms.
  • Severe: syndromes such as Stevens–Johnson syndrome (SJS), toxic epidermal necrolysis (TEN), drug rash with eosinophilia and systemic symptoms (DRESS), and other organ‑involving reactions.

If you have ever had a severe delayed reaction like SJS, TEN, or DRESS, you should never take penicillin or undergo penicillin challenge testing again.

What is not a true allergy?

Many reactions blamed on penicillin are not immune allergies at all. Examples include:

  • Nausea, vomiting, or diarrhea without other symptoms
  • Headache or fatigue
  • Yeast infections after antibiotics
  • A viral rash that happened to appear while taking penicillin
  • A family history of penicillin allergy without any reaction yourself

These situations often can be “delabeled” simply by reviewing your history with a clinician, sometimes backed up by a supervised single‑dose challenge.

How can I find out if I am really allergic?

National allergy organizations recommend that penicillin allergy evaluations be offered proactively, even before you need antibiotics. This can usually be done in three steps.

  1. Detailed history

Your clinician or allergist will ask about:

  • What penicillin drug you took (for example, amoxicillin)
  • What happened, including your symptoms
  • How long after taking the dose the symptoms started
  • How many years ago this occurred
  • Whether you have taken any penicillin‑type or cephalosporin antibiotics since then without issues

Many people with only vague, mild, or very remote skin‑only reactions (more than five years ago) are considered “low risk.”

  1. Skin testing (when needed)

For patients with a higher‑risk history — like hives, wheezing, or a concerning recent reaction — penicillin skin testing is often recommended.

  • Small amounts of penicillin test reagents are placed on or just under the skin.
  • The allergist watches for a localized hive reaction that suggests allergy.
  • If skin testing is negative, the next step is usually an oral challenge.

Penicillin skin testing has a very high negative predictive value, meaning that if your test is negative and you pass an oral challenge, your risk of an allergy reaction is similar to someone with no history at all.

  1. Direct oral challenge

For many low‑risk patients, guidelines now support a direct supervised oral challenge with a penicillin such as amoxicillin, sometimes without prior skin testing.

  • You take a small dose under observation, then a full dose if there is no reaction.
  • Staff monitor you for a set period for any signs of allergy.
  • If you tolerate it, the penicillin allergy label can usually be removed from your chart.

People with a history of severe delayed reactions (SJS, TEN, DRESS, severe organ injury) should not undergo this kind of challenge.

If my test is negative, is it safe to use penicillin?

When skin testing (if done) and an oral challenge are negative, you can typically use penicillin and related antibiotics when needed. Research shows that these patients do not have a higher risk of immediate IgE‑mediated reactions than the general population.

It is important to have your medical records updated to remove the penicillin allergy label and document your testing results clearly so the allergy is not accidentally re‑added in the future.

What if I truly am allergic and need penicillin?

Sometimes penicillin is the only recommended treatment, such as for neurosyphilis or syphilis in pregnancy. If you have a confirmed penicillin allergy and no good alternative antibiotic:

  • You may undergo a process called desensitization in a monitored hospital setting.
  • Tiny, gradually increasing doses of penicillin are given over hours until the full dose is reached.
  • This temporarily trains your immune system to tolerate the drug so the course can be completed safely.

Desensitization does not “cure” the allergy permanently, so you should continue to be labeled allergic unless retested and advised otherwise by an allergist.

When should I talk to a doctor about penicillin allergy?

You should seek medical advice if:

  • You have a penicillin allergy label but do not clearly remember the reaction.
  • Your reaction happened in childhood or more than five to ten years ago.
  • Your reaction was just stomach upset, a mild rash, or a family history.
  • You are pregnant or planning surgery and carry a penicillin allergy label.
  • You have had a concerning reaction such as hives, wheezing, swelling, or feeling faint after penicillin.

An allergist or knowledgeable clinician can help decide whether you should be delabeled by history, undergo a supervised oral challenge, have formal skin testing, or continue to avoid penicillin. Early evaluation — before you urgently need antibiotics — gives you more options and time to make a safe plan.

If you carry a penicillin allergy label or are unsure about a past reaction, schedule an appointment with us today to review your history and discuss testing options so you can safely expand your future antibiotic choices.

Sources

  1. CDC – Clinical Features of Penicillin Allergy (Antibiotic Prescribing and Use)​
  2. StatPearls – Penicillin Allergy (NCBI Bookshelf)​
  3. AAAAI – Penicillin Allergy evaluation/position statement and public guidance (American Academy of Allergy, Asthma & Immunology
Peanut allergy prevention through early introduction

Can Feeding My Child Peanuts Early Prevent Peanut Allergy?

January 1, 2026/in News

 

Many parents ask: “When should I introduce peanuts to my child?” and “Will early introduction really prevent peanut allergies?” These questions reflect a significant shift in how we approach food allergies in infants. The answer is encouraging and backed by substantial research. Recent evidence shows that introducing peanuts early in your infant’s diet can significantly reduce the risk of developing peanut allergy, contradicting decades of previous advice that recommended delayed introduction. 

Understanding the Peanut Allergy Problem

Peanut allergies have become increasingly common over the past few decades, affecting approximately 2% of children in the United States. Unlike some childhood allergies that children may outgrow, peanut allergies typically persist into adulthood. These allergies can cause severe, life-threatening reactions, making prevention a critical public health priority.

For years, parents were advised to delay introducing peanuts and other allergenic foods until after their child’s first birthday, or even later for high-risk children. This guidance, it turns out, may have actually contributed to the rising rates of peanut allergies we’ve seen in recent decades. 

The Groundbreaking LEAP Study Changed Everything

A landmark 2015 study called the Learning Early About Peanut Allergy (LEAP) study fundamentally changed how we approach peanut allergies in children. Published in the New England Journal of Medicine, this research demonstrated that early introduction of peanuts is not only safe but highly effective at preventing allergies.

The LEAP study, conducted by researchers at King’s College London, enrolled over 600 infants between 4 and 11 months of age who were considered at high risk for developing peanut allergy due to severe eczema, egg allergy, or both. The children were randomly assigned to either consume or avoid peanut products until 5 years of age.

The results were remarkable and unexpected. Among children who avoided peanuts, 17.2% developed peanut allergy by age 5. In stark contrast, only 3.2% of children who regularly consumed peanut products developed the allergy. This represented an 81% reduction in peanut allergy development among high-risk infants who consumed peanuts early and regularly.

 Current Guidelines Reflect This Research

Following the LEAP study results, major health organizations revised their recommendations. In 2017, the National Institute of Allergy and Infectious Diseases (NIAID) released updated guidelines endorsing early peanut introduction for most infants.

The American Academy of Pediatrics (AAP) similarly updated its guidance, recommending that peanut-containing foods be introduced to infants around 6 months of age, and potentially as early as 4 months for high-risk infants, after other solid foods have been tolerated.

These guidelines represent a complete reversal from previous recommendations and are based on strong scientific evidence showing that early introduction helps the immune system develop tolerance rather than sensitivity to peanuts. 

Real-World Results Are Proving the Guidelines Work

The results are striking and demonstrate that these guidelines are translating into meaningful public health benefits. According to a 2025 study from Children’s Hospital of Philadelphia (CHOP) published in Pediatrics, peanut allergy rates in children under three years old have declined by 43% over the last several years since these new guidelines were implemented.

This study analyzed data from over 1.3 million children and found clear evidence that the widespread adoption of early peanut introduction has led to a substantial decrease in peanut allergy prevalence. The research provides real-world confirmation that what worked in controlled clinical trials is equally effective when applied across diverse populations in everyday settings.

Early Introduction Prevents Other Food Allergies Too

The benefits of early allergen introduction extend beyond peanuts. The same CHOP study found that early introduction practices led to a 36% reduction in all new cases of food allergies, including common allergens like milk, egg, and tree nuts.

Additional research, including the Enquiring About Tolerance (EAT) study published in the New England Journal of Medicine, examined the early introduction of six allergenic foods: peanut, egg, cow’s milk, sesame, whitefish, and wheat. While the results were less dramatic than the LEAP study due to adherence challenges, the research supported the safety and potential benefits of early introduction for multiple foods.

How to Safely Introduce Peanuts to Your Child

Current guidelines from the NIAID recommend introducing small amounts of peanut-containing foods early in an infant’s life, with the timing dependent on the child’s risk level:

Low-risk infants (those without eczema or known food allergies) can have peanut-containing foods introduced around 6 months of age, along with other solid foods, according to family preferences and cultural practices.

Moderate-risk infants (those with mild to moderate eczema) should have peanut-containing foods introduced around 6 months of age, after other solid foods have been tolerated.

High-risk infants (those with severe eczema, egg allergy, or both) should have peanut introduction as early as 4 to 6 months of age, but only after evaluation by an allergist or healthcare provider. Some high-risk infants may need supervised introduction or testing before home introduction.

This careful, gradual approach helps the immune system develop tolerance rather than triggering allergic reactions later. The key is starting early and introducing these foods in age-appropriate forms consistently, ideally at least three times per week.

Age-Appropriate Forms of Peanut Products

For infants, whole peanuts and chunky peanut butter pose a choking hazard and should never be given to young children. Instead, parents should use:

Smooth peanut butter thinned with water, breast milk, or formula to achieve a consistency the infant can safely swallow. Start with about 2 teaspoons of smooth peanut butter mixed with 2 to 3 teaspoons of liquid.

Peanut powder or peanut flour mixed into purees, cereals, or other age-appropriate foods.

Peanut puff snacks specifically designed for infants and young children, which dissolve easily in the mouth.

The goal is to provide approximately 2 grams of peanut protein three times per week. Once introduced, peanut-containing foods should be maintained regularly in the child’s diet to sustain tolerance.

What to Watch For During Introduction

When introducing peanuts for the first time, parents should watch for signs of an allergic reaction, which may include hives or skin rash, swelling of the lips, face, or tongue, vomiting or diarrhea, coughing or wheezing, or difficulty breathing.

Most reactions occur within minutes to two hours after exposure. The AAP recommends introducing peanut products at home rather than at a daycare or restaurant, when the child is healthy, and when a parent can watch the child for at least two hours afterward.

If any signs of an allergic reaction occur, parents should stop feeding the child and seek medical attention immediately. Severe reactions require calling 911.

Special Considerations for High-Risk Infants

For infants with severe eczema, egg allergy, or both, consultation with an allergist before introducing peanuts at home is strongly recommended. An allergist may perform testing such as a skin prick test or blood test to assess the likelihood of peanut allergy.

Based on these results, the allergist may recommend supervised introduction in the office, where emergency treatment is immediately available if needed, or may clear the child for introduction at home with specific instructions.

When to Seek Professional Guidance

If you feel nervous about introducing highly allergenic foods to your infant, you’re not alone. Many parents have questions about timing, preparation, and what to watch for during introduction.

At Vallen Allergy and Asthma, we help parents navigate early food introduction safely. We can discuss your child’s individual risk factors, review their medical history including any eczema or other food allergies, create a personalized introduction plan, and provide support throughout the process.

Professional guidance is particularly important for high-risk infants or if you have concerns about your child’s readiness for solid foods.

Conclusion: Evidence-Based Prevention Is Working

The dramatic 43% decline in peanut allergies among young children represents a major public health success story. By following evidence-based guidelines for early peanut introduction, parents can significantly reduce their child’s risk of developing this potentially dangerous allergy.

Don’t let uncertainty prevent you from giving your child the best protection against food allergies. Contact us to discuss your options and get answers to your questions about early allergen introduction.

Sources:

  • Du Toit G, et al. New England Journal of Medicine, 2015 (LEAP Study)
  • National Institute of Allergy and Infectious Diseases (NIAID) Addendum Guidelines, 2017
  • American Academy of Pediatrics Clinical Guidelines
  • Perkin MR, et al. New England Journal of Medicine, 2016 (EAT Study)
  • Children’s Hospital of Philadelphia, Pediatrics, 2025

Welcome Claire Lyons to the VAA team

September 1, 2024/in News

Vallen Allergy and Asthma welcomes Claire Lyons to the team of professionals.

claire lyons headshotClaire is an American Academy of Nurse Practitioners board certified Family Nurse Practitioner with a special interest in allergy and immunology. She is a summa cum laude graduate of Providence College where she received her Bachelor of Science in Biology. She then went on to receive her BSN and MSN from MGH Institute of Health Professions and has been working as a Nurse Practitioner in Allergy ever since.

When she is not in the office, you can most likely find Claire perfecting her cake decorating skills or spending time with her family.

Living With Food Allergies Complementary Workshop

June 9, 2024/in News

Please join us for a complimentary workshop by, Peyton Lessard, MS Peyton earned her degree in Nutrition communications and behavior change from Tufts University. During this presentation Peyton will discuss all areas of nutrition when living with a food allergy. This presentation will give you an overview of what a food allergy is, highlight food safety concerns, offer allergy-friendly snacks and alternatives, allergen-free brands to look out for, and more!

To attend this event and reserve your spot, Please RSVP by contacting us today.

living with allergies complementary workshop

May is Food Allergy Awareness Month

May 1, 2023/in News

One in thirteen Children have a Food Allergy.  VAA offers accurate diagnosis and treatment options.  Watch this food allergy awareness video from Dr. Margaret Vallen to learn more.

Working Hours

Monday 9:00am - 5:00pm
(Injections 9:30am - 11:45am & 1:00pm - 4:30pm)
Tuesday 9:00am - 4:30pm
(Injections 1:00pm - 4:30pm)
Wednesday 9:00am - 7:30pm
(Injections 1:00pm - 6:45pm)
Thursday 9:00am - 4:30pm
(Injections 9:00am - 11:45am)
Friday 9:30am - 12:30pm
Saturday CLOSED
Sunday CLOSED

Vallen Allergy & Asthma, PC, is a leading allergy and asthma specialty practice in Quincy, MA.

For over 32 years, the office has been serving children and adults in southern and southeastern Massachusetts.

ABOUT VALLEN ALLERGY & ASTHMA

700 Congress St, Suite 301

Quincy, MA 02169

Phone : 617.472.7111
Fax : 617.376.2344

Opening Hours

Monday 9:00 am – 5:00 pm
Tuesday 9:00 am – 4:30 pm
Wednesday 9:00 am – 7:30 pm
Thursday 9:00 am – 4:30 pm
Friday 9:30 am – 12:30 pm
Saturday CLOSED
Sunday CLOSED
Copyright © 2025 - Vallen Allergy & Asthma CenterPatient PolicyPrivacy Policy
  • Facebook
  • Instagram
Scroll to top