Is Azithromycin Related to Penicillin? A Guide for Antibiotic Users

Antibiotics are drugs that can treat bacterial infections, such as ear infections, sinus infections, urinary tract infections, and food poisoning. However, not all antibiotics are the same. Some people may be allergic to certain types of antibiotics, such as penicillin, and need to use alternative drugs. One of the common questions that antibiotic users may have is: is azithromycin related to penicillin? This article will answer this question and provide some useful information for antibiotic users.

What is Penicillin?

Penicillin is a group of antibiotics that contain a chemical structure called a beta-lactam ring. Penicillin was the first antibiotic discovered in 1828 and has been used to treat many types of bacterial infections. Some of the most common penicillin antibiotics are:

  • Penicillin
  • Ampicillin
  • Amoxicillin
  • Methicillin

Penicillin works by interfering with the cell wall synthesis of bacteria, causing them to burst and die. Penicillin is often the first choice for treating infections of the ear, nose, throat, lungs, sinuses, and urinary tract.

What is Azithromycin?

Azithromycin is a different type of antibiotic that belongs to a group called macrolides. Azithromycin was first introduced in 1988 and is also used to treat various bacterial infections, such as:

  • Bronchitis
  • Pneumonia
  • Chlamydia
  • Gonorrhea
  • Lyme disease
  • Pertussis

Azithromycin works by inhibiting the protein synthesis of bacteria, preventing them from growing and multiplying. Azithromycin is often prescribed as a single dose or a short course of treatment, which makes it convenient and effective.

Is Azithromycin a Penicillin?

The answer is no. Azithromycin is not a penicillin antibiotic and does not contain penicillin. Azithromycin and penicillin have different chemical structures, mechanisms of action, and spectrum of activity. Therefore, they are not related to each other.

Can You Take Azithromycin if You are Allergic to Penicillin?

The answer is yes, in most cases. According to, over 95 percent of people with penicillin allergy can safely take azithromycin or other macrolide antibiotics. This is because the risk of cross-reactivity between penicillin and azithromycin is very low. Cross-reactivity means that a person who is allergic to one drug may also be allergic to another drug that has a similar structure or function.

However, some people may still have an allergic reaction to azithromycin or other antibiotics, even if they are not allergic to penicillin. This is because allergies are unpredictable and can vary from person to person. Therefore, it is important to inform your doctor about any drug allergies or medical conditions you have before taking any antibiotic. You should also watch out for any signs of an allergic reaction, such as:

  • Hives
  • Swelling of the face, throat, hands, or feet
  • Wheezing, chest tightness, or difficulty breathing
  • Nausea, vomiting, or diarrhea
  • Dizziness, weakness, or loss of consciousness

If you experience any of these symptoms, you should stop taking the antibiotic and seek medical attention immediately.


Azithromycin is not related to penicillin and can be used as an alternative antibiotic for people who are allergic to penicillin. However, azithromycin may still cause allergic reactions in some people, so it is important to consult your doctor before taking any antibiotic and follow the instructions carefully. Antibiotics are powerful drugs that can help you fight bacterial infections, but they should be used wisely and responsibly.