I’m seeing, reading, and hearing a lot about zinc in the prevention and management of various infectious diseases such as COVID and head colds. While I’m not very sold on the data supporting its use, there will be patients that are going to try it. It is critical to remember that if you have patients taking zinc, it is not without risks. I outline a few common zinc drug interactions below.
Virtually all the clinically significant zinc drug interactions are in relation to zinc binding up other medications.
Baloxavir is a relatively newer agent used in the management of influenza. Zinc can bind the drug and it is an absolute contraindication to use them together. If patients begin taking zinc for head cold type symptoms and then they are actually diagnosed and treated for influenza, be sure to remember to have them stop taking their zinc as it will essentially leave baloxavir ineffective.
Most patients who are taking bisphosphonates like alendronate are usually well aware of avoiding other medications and supplements when taking their commonly used weekly dose.
Drugs like doxycycline can also be bound up by zinc. It is important to recognize that upper respiratory infections can start out with head cold type symptoms to which patients may begin to take zinc. If they are later diagnosed with pneumonia or another bacterials URI, doxycycline may be utilized to manage the infection.
Not all cephalosporins are affected by zinc administration but one of the common ones in cephalexin can be. I’d recommend looking it up with each individual cephalosporin as you come across them. Also recall that this binding interaction happens in the GI tract so parenteral administration would avoid this issue.
Quinolones are being used a little more in inpatient settings compared to outpatient settings over the last several years. However, oral options still exist and you will see them used periodically for more serious infections. Zinc can reduce the absorption of oral quinolone antibiotics.
Medication adherence and adequate drug concentrations are critical in HIV management. The integrase inhibitors like dolutegravir, bictegravir, and elvitegravir can all have their concentrations reduced due to zinc co-administration.
I’ve encountered numerous patients taking zinc and we have to remind them that zinc drug interactions are relatively common and can adversely affect their other medications.
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