Underlying Disease
Hives may be caused by an underlying medical condition, but this is rare. This is more common in people who have chronic urticaria, i.e. hives that last more than six weeks. While most cases of chronic urticaria are not caused by diseases or infections, a few are. You should try to rule them out. Underlying diseases [11] that may trigger hives include type 1 diabetes, thyroid disease, celiac disease, hepatitis, cancer, lupus, and rheumatoid arthritis. Bacterial infections can also cause urticaria. [12]
Conclusion
The exact cause of hives is not always clear and several factors can trigger an incidence. These triggers are not the same for everyone. It is important to learn which situations trigger your symptoms and try to avoid them. If your hives get too uncomfortable, take long to resolve and you cannot narrow the trigger down to anything, you should see a doctor.
Reference:
[1] https://www.medicinenet.com/hives/article.htm
[2] https://www.medicalnewstoday.com/articles/157260
[3] https://acaai.org/allergies/types-allergies/hives-urticaria
[4] https://acaai.org/allergies/types-allergies/hives-urticaria
[5] https://www.webmd.com/skin-problems-and-treatments/guide/hives-urticaria-angioedema
[6] https://acaai.org/allergies/types-allergies/hives-urticaria
[7] https://acaai.org/allergies/types-allergies/hives-urticaria
[8] https://www.medicalnewstoday.com/articles/157260
[9] https://www.medicalnewstoday.com/articles/157260
[10] https://www.medicalnewstoday.com/articles/157260
[11] https://www.healthline.com/health/hives
[12] https://acaai.org/allergies/types-allergies/hives-urticaria