Updated

According to the Centers for Disease Control and Prevention, COVID-19 symptoms usually include fever, cough, aches and difficulty breathing, among others. A new study, however, suggests that skin rashes, which are not listed by the CDC, are also a sign of the deadly virus.

The research, published in JAMA Dermatology, notes that enanthems (skin rash-like lesions inside a person's mouth) were observed in some (6 of 21) patients with COVID-19 and skin rash. The patients were aged between 40 and 69 and four of the six were female.

"This work describes preliminary observations and is limited by the small number of cases and the absence of a control group," researchers from Ramon y Cajal University Hospital in Madrid wrote in the study. "Despite the increasing reports of skin rashes in patients with COVID-19, establishing an etiological diagnosis is challenging. However, the presence of enanthem is a strong clue that suggests a viral etiology rather than a drug reaction, especially when a petechial pattern is observed."

'VAST MAJORITY' OF COVID-19 PATIENTS HAVE ANTIBODIES FOR AT LEAST 3 MONTHS: STUDY

The researchers added that "many patients with suspected or confirmed COVID-19 do not have their oral cavity examined," largely due to safety concerns. Given the fact that patients are wearing masks and the mouth is not examined, it's possible additional COVID-19 patients may have these symptoms.

The rashes were split into four different categories, according to the researchers: "petechial, macular, macular with petechiae, or erythematovesicular.”

Enanthems were previously identified in some COVID-19 patients in Italy, the researchers explained.

CDC'S 'BEST ESTIMATE' IS 40 PERCENT COVID-19 INFECTIONS ARE ASYMPTOMATIC

In June, the CDC added congestion or runny nose, nausea, and diarrhea to its ongoing list of COVID-19 symptoms, Fox News reported.

In April, a separate group of scientists in Spain found lesions on feet they said may be linked to the novel coronavirus.

A CDC spokesperson pointed Fox News to the list of symptoms associated with COVID-19 and did not comment on the study.

CLICK HERE FOR COMPLETE  CORONAVIRUS COVERAGE

As of Monday morning, more than 14.5 million coronavirus cases have been diagnosed worldwide, more than 3.7 million of which are in the U.S., the most impacted country on the planet.

GET THE FOX NEWS APP

Fox News' Madeline Farber contributed to this story.