VIDEO - LA doctor seeing success with hydroxychloroquine to treat COVID-19 - ABC7 Los Angeles

LOS ANGELES (KABC) -- A Los Angeles doctor said he is seeing significant success in prescribing the malaria drug hydroxychloroquine in combination with zinc to treat patients with severe symptoms of COVID-19.

Hydroxychloroquine has been touted as a possible treatment for COVID-19 by President Trump among others, but it remains controversial as some experts believe it is unproven and may not be effective.

The drug has long been used for treatment of malaria and conditions such as lupus and arthritis but is not technically approved by the FDA for COVID-19. The agency, however, is encouraging trials and has provided

limited emergency authorization

for its use to treat COVID-19 patients.

Dr. Anthony Cardillo said he has seen very promising results when prescribing hydroxychloroquine in combination with zinc for the most severely-ill COVID-19 patients.

"Every patient I've prescribed it to has been very, very ill and within 8 to 12 hours, they were basically symptom-free," Cardillo told Eyewitness News. "So clinically I am seeing a resolution."

Cardillo is the CEO of Mend Urgent Care, which has locations in Sherman Oaks, Van Nuys and Burbank.

He said he has found it only works if combined with zinc. The drug, he said, opens a channel for the zinc to enter the cell and block virus replication.

He added that the drug should not be prescribed for those who are presenting only mild symptoms, as there are concerns about shortages for patients with other conditions who need to take the drug on a regular basis.

"We have to be cautious and mindful that we don't prescribe it for patients who have COVID who are well," Cardillo said. "It should be reserved for people who are really sick, in the hospital or at home very sick, who need that medication. Otherwise we're going to blow through our supply for patients that take it regularly for other disease processes."

Full interview: Dr. Anthony Cardillo of Mend Urgent Care in Los AngelesChloroquine, or hydroxychloroquine, has been approved to treat and prevent malaria since 1944. Because the drug is on the market, doctors can use it for off-label purposes.

President Trump has touted it as a possible cure, but the government's top coronavirus expert, Dr. Anthony Fauci, has been much more cautious, saying there is only "anecdotal evidence" demonstrating its effectiveness.

Experts are also concerned about potential misuse. A man in Arizona died after taking what he thought was a similar substance, chloroquine phosphate, in an apparent attempt to self-medicate. The man did not take the pharmaceutical version of the drug, but a substance used at aquariums to clean fish tanks.

MORE: Chloroquine shortage concerns mount as Trump touts malaria drug as possible COVID-19 treatmentThe FDA advises against taking any form of chloroquine unless prescribed by a doctor and obtained from a legitimate source.

Another drug that has shown some potential for treating COVID-19 is remdesivir, a drug that was initially developed as a potential treatment for Ebola. A Palo Alto woman was accepted into a clinical trial for remdesivir and said it was effective in improving her condition.

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