Urticaria: Allergic Reactions or Medication Side Effects?

Q: Urticaria: Allergic Reactions or Medication Side Effects?

Hello： Cephalosporins and penicillins have similar structures, and individuals who are allergic to one type have a 10-20% chance of being allergic to the other type of antibiotic. <br>Therefore, it is indeed possible that you may also have an allergy to penicillin antibiotics. <b

Is it simple urticaria, a drug allergy, or a side effect of antithyroid medication?

I started experiencing hyperthyroidism on April 2nd and began taking Levothyroxine, one tablet twice a day, and Metoprolol, one to two tablets daily.
On April 20th, a Bartholin gland cyst recurred, and I underwent aspiration at the gynecology department.
The doctor prescribed medication: Gastricain, one tablet three times a day; Clonazepam, one tablet three times a day; and Lydocaine capsules, two tablets four times a day.
On April 21st, I returned to the hospital for another aspiration, and the doctor added medication: Norfloxacin 1000 mg, one tablet twice a day.
I took the medication until April 22nd, when I started feeling itchy at 4 PM.
After 5 PM, I began developing a rash, so I went to the hospital for medication: I took one tablet of Benadryl, and by 8 PM, the rash had completely disappeared.
At 9 PM, I needed to take medication and was concerned that the antibiotic might have caused an allergic reaction, so I stopped taking Norfloxacin and only took two tablets of Lydocaine.
At 3 AM, I felt unwell, and my body was covered in hives.
I went to the hospital for a muscle injection of an antihistamine and took one tablet of Benadryl and one tablet of Loratadine.
An hour later, the rash completely disappeared.
On the morning of the 23rd, I only took one tablet of Levothyroxine and did not dare to take any other medications.
By noon, no rash had appeared.

Doctor, my concern is regarding the antibiotics.
I am only allergic to antibiotics related to "Staphylococcus," and I have taken other antibiotics in the past without any allergic reactions.
Why did this happen this time? Is it related to my hyperthyroidism, or has my constitution changed, leading to allergies to other antibiotics? Or is it simply a case of urticaria? Additionally, if I am allergic to Staphylococcus-related antibiotics, should I also avoid penicillin antibiotics? I have many questions; thank you for your help.

A Yao, 30~39 year old female. Ask Date: 2021/04/23

Dr. Lin Wufu reply Internal Medicine

Hello: Cephalosporins and penicillins have similar structures, and individuals who are allergic to one type have a 10-20% chance of being allergic to the other type of antibiotic.
Therefore, it is indeed possible that you may also have an allergy to penicillin antibiotics.
It is recommended that you mark this on your health insurance card to alert healthcare providers when prescribing medications.
Additionally, many people are only allergic to certain specific antibiotics within the same class, so it is advisable not to simply remember that you are allergic to cephalosporins, but to note which specific cephalosporin you are allergic to.
Similarly, being allergic to "Norfloxacin" does not necessarily mean you are allergic to all penicillin antibiotics, so it is best to document the generic name of the allergic medication for the physician's reference.

Reply Date: 2021/04/23

More Info

Urticaria, commonly known as hives, can be a complex condition often triggered by various factors, including allergic reactions to medications, food, or environmental allergens. In your case, the timeline of events suggests a potential link between the medications you were prescribed and the onset of urticaria.

From your description, it appears that you began experiencing symptoms of urticaria shortly after starting a regimen that included multiple medications, particularly antibiotics such as Norfloxacin and Lidaoxin. While you have a known allergy to a specific class of antibiotics (the "head苞子菌" or "head bacteria" antibiotics, which I assume refers to a specific type of antibiotic), it is important to note that allergic reactions can develop to other medications even if you have previously tolerated them without issues. This phenomenon is known as sensitization, where the immune system becomes reactive to a substance after previous exposure.

The fact that you experienced itching and hives after taking Norfloxacin, and that symptoms resolved after stopping the medication, strongly suggests that this antibiotic could be the culprit. However, it is also possible that the combination of medications, including those for thyroid management and the treatment for the Bartholin gland cyst, could have contributed to your symptoms.
Regarding your question about whether your hyperthyroidism could be related to the urticaria, there is no direct correlation between hyperthyroidism and the development of hives. However, stress and hormonal changes associated with thyroid disorders can influence the immune system, potentially making you more susceptible to allergic reactions. Additionally, any underlying changes in your body’s immune response due to thyroid dysfunction could also play a role.

As for your concern about whether you should avoid penicillin antibiotics due to your allergy to the "head苞子菌" antibiotics, it is advisable to exercise caution. Allergies to one class of antibiotics can sometimes indicate a higher likelihood of reactions to other classes, particularly those that share similar structures, such as penicillins. It is essential to inform your healthcare provider about your specific allergies so they can prescribe alternatives that are safe for you.

In summary, your urticaria appears to be a reaction to one or more of the medications you were taking, particularly the antibiotics. It is crucial to monitor your symptoms and avoid any medications that have previously caused allergic reactions. If you experience hives again or have concerns about your medications, consult with your healthcare provider or an allergist for further evaluation and management. They may recommend allergy testing to identify specific sensitivities and help guide your future treatment options.

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