Although the use of Pfizer Inc’s (PFE.N) COVID-19 antiviral Paxlovid increased this week, some doctors are reconsidering the pills for lower-risk patients after a US public health official warned that symptoms sometimes reappear after people finish a course of the treatment and that they should isolate again.

Dr. Sandra Kemmerly, an infectious disease specialist at Ochsner Health in New Orleans, told Reuters that more quarantine time “is not a crowd-pleaser.” “For those who aren’t in immediate danger, I would advise them not to take it.”

As infections have increased, so has the use of Pfizer’s Paxlovid, which is approved to treat newly infected, at-risk persons in order to prevent serious disease. According to official data, more than 162,000 courses were administered last week, compared to an average of 33,000 per week since the drug’s debut late last year. Officials in the Biden administration have pushed for widespread use of Paxlovid, which the government buys and distributes for free.

However, increased use has resulted in more reports from people who believe their symptoms improved after taking Paxlovid for five days, only to return a few days later.

The Centers for Disease Control and Prevention (CDC) issued a caution on Tuesday, citing case reports and worries that relapsed patients could spread the virus, advising Paxlovid users to isolate for a second five days if symptoms return.