With cold and flu season in full swing, you might be turning to zinc for some extra protection. The mineral is important for immune function, so it’s a popular supplement or additive to lozenges, gummies, powders, and other immunity-boosting products.

However, if you’re adding zinc to your daily routine, it’s important to first assess your current supplement and medication regimen—combining zinc with certain products could lead to unintended consequences.

If you’re taking any of these four drugs and supplements, you may want to think twice about starting a zinc supplement, experts said.

Iron is a crucial ingredient in hemoglobin, a red blood cell protein that helps move oxygen from the lungs to other cells in the body. It’s also important for hormone production.

However, iron can inhibit the body’s ability to absorb zinc. In fact, research has shown that taking an iron supplement over 25 milligrams (mg) can lead to lower zinc concentrations in the body.

Interestingly, the inverse doesn’t seem to be true—research is mixed, but most studies show zinc supplements don’t have any negative effect on iron levels.

But if you’re looking to see maximum benefits from both your iron and zinc supplements, it’s best not to take them together.

Magnesium is a popular supplement for sleep and relaxation, and it’s also involved in the regulation of blood sugar levels, muscle and nerve function, and other important bodily processes.

But taking high doses of zinc—at least 142 mg per day via a supplement—can affect magnesium absorption and balance in the body.

Calcium is important for keeping your bones and teeth healthy. But like the other minerals on this list, taking zinc and calcium at the same time may not be the best choice.

Some research suggests that taking high doses of calcium can affect the body’s absorption of zinc. This has also been shown in animal studies.

However, other research has found the opposite—participants who took more didn’t see any changes to their zinc levels. The interaction between these two minerals is something that scientists are continuing to study.

Depending on the kind of antibiotics you’re taking, you may want to avoid zinc.

The mineral can interact with quinolone antibiotics (like Cipro), which are used to treat a wide range of bacterial infections, including urinary tract infections, Maria Pino, PhD, pharmacist and associate professor at New York Institute of Technology, told Health.

The same is true for tetracyclines, another class of antibiotics used to treat acne and other infections.

“Zinc would decrease the efficacy of the antibiotic,” Pino said. “It wouldn’t cause true harm, but it would not make the drug effective, and that could lead to not getting better.”

And these interactions are a two-way street: Antibiotics could impair the body’s ability to absorb zinc, too.

In the body, zinc is usually divalent, which means it has a positive charge. The same is true for magnesium, calcium, and iron.

Because these minerals all have similar electric charges, they all rely on the same proteins to move from the gut into the bloodstream, explained Erin Barrett, PhD, nutritional biochemist and senior director of product innovation and scientific affairs at Shaklee, a supplement company.

An excess of minerals trying to simultaneously catch a ride on the same transport protein means the body can’t take in everything. Essentially, “other minerals can compete for absorption with zinc,” Barrett told Health.

It’s similar for quinolone and tetracycline antibiotics—these drugs don’t necessarily compete with zinc, but they can bind to these positively-charged minerals. This creates a molecule that the body can’t absorb well.

These absorption issues aren’t necessarily dangerous, but they could be a concern for people with nutritional deficiencies or those trying to treat an infection.

Minerals are naturally occurring in food, but harmful interactions or absorption issues usually don’t happen. The problem arises more so with supplements, since “you’re providing a very high percentage of the daily value of that mineral,” Barrett said.

That means it’s best to get the zinc and other minerals you need from your diet. Good sources of zinc include:

Meanwhile, yogurt and milk are good sources of calcium, lean meat and nuts contain iron, and seeds and leafy greens are full of magnesium.

But it’s not always possible to get enough vitamins and minerals from what we eat. “Iron, calcium, and magnesium are nutrients that a lot of us don’t get enough of from our diet,” Barrett explained, so some people need an extra dose from a supplement.

If that’s the case—or if you’ve been prescribed an antibiotic—experts recommended taking a zinc supplement separately from other medications and supplements, spacing them out by about two to four hours. You may also want to purchase individual mineral supplements rather than taking a multivitamin, Barrett added.

“You could split them up: Take the zinc in the morning, and a couple hours later or in the evening, you could take the calcium,” she said.

Of course, it’s crucial that you speak to a doctor before starting zinc or any other supplements, particularly if you’re already taking other drugs or supplements, Pino added.