(Reuters Health) - Secondhand marijuana smoke appears to have provoked a cannabis allergy and worsened the asthma of a 6-year-old child, researchers told the American College of Allergy, Asthma, and Immunology’s annual conference in Seattle.

A man smoking marijuana through a mask during a Global March for marijuana in Bogota, Colombia, May 5, 2018. REUTERS/Jaime Saldarriaga

The findings may be the first reported case of cannabis allergy in a child, the researchers said November 16 as they described the details.

The young patient had poorly controlled asthma and lived with adult family members who often smoked marijuana at home. The boy’s grandmother also had a history of hives after smoking marijuana. Skin prick tests and blood tests confirmed that both the boy and his grandmother were allergic to cannabis.

The boy’s asthma improved after family members stopped smoking cannabis in the home, as confirmed by further medical tests and reports from the family.

“Children exposed to secondhand marijuana smoke can become allergic to cannabis, which in turn may significantly worsen their asthma or allergy symptoms,” said the report’s lead author Dr. Bryce Hoffman, an Allergy and Immunology Fellow at National Jewish Health in Denver, Colorado. “This is particularly concerning as the cannabis may not be suspected as a cause.”

Doctors should consider the possibility of cannabis allergy in any child with uncontrolled asthma who is being exposed to secondhand marijuana smoke, Hoffman told Reuters Health by email. “This includes any use of marijuana in the household where the patient lives. These children should be referred to an allergist for further work-up.”

The problem may become more widespread as exposure rates increase with the trend toward cannabis legalization in U.S. states and other countries, Hoffman noted.

This study highlights the fact that allergists need to ask about patients’ exposure to marijuana smoke, said Dr. Janna Tuck, an allergist at Allergy Partners of New Mexico in Santa Fe, who was not involved in the case report.

“If they don’t, they could miss a significant trigger for asthma and other allergy symptoms,” Tuck said.

SOURCE: bit.ly/2qZ3UNn Annals of Allergy, Asthma & Immunology, November 2018.