The vitamin and supplement industry is big business. Over the course of a lifetime, most of us will take many of these products to enhance our health, improve our well-being, or manage certain symptoms with a “natural” remedy. In fact, Americans spend over $23 billion a year on these products. We often find the “natural” labeling reassuring. Many people swear that these products work wonders.

And since vitamins and supplements are not regulated the same way drugs are regulated in this country and because anybody can purchase them from stores and online sources, it is easy to think that these are harmless products.

That’s not actually the case. So while it may be a good idea for you to take these drugs, you should tell your doctor (and pharmacist) what you are taking. Here are four reasons to tell your doctor or nurse about the supplements you take.

1. Even something as seemingly benign as a vitamin pill can have a toxic effect on the body when excessive amounts are taken. In fact, some vitamins in megadoses can cause serious side effects and even be lethal. Read labels and literature carefully. If you are taking vitamins, tell your doctor not just the kind, but also the dose.

2. Some commonly available supplements have definite side effects that consumers may not be aware of. For instance, colloidal silver (which is readily available) can cause the skin to turn blue—and it’s a permanent change that can only be fixed with expensive laser treatments. Why don’t more people know about this “blue skin” risk with colloidal silver, which is sold for immune support? The FDA issued a warning back in 2009, but how many of us are regular readers of the FDA website?

The product is not considered dangerous enough to ban. If you take supplements, tell your doctor, since he or she is likely more up-to-date with potentially risky supplements. (You may wonder why the FDA does not simply ban supplements like colloidal silver, but the fact is, it takes a lot of evidence, study, and expense to get a substance like that off the market. The FDA did get ephedra, a weight-loss supplement, off the market but it took thousands of adverse events to do so.)

3. Some supplements can potentially interact with drugs you already take. In such cases, the supplement may be safe and the drug may be safe, but they do not work well together.

4. Some supplements and vitamins can cause symptoms. For instance, peppermint essential oil in high doses can cause heart burn. The oil can relax certain smooth muscles, and in the case of the digestive system, that is not the ideal situation. If you go to the doctor with heart burn, he or she may prescribe a drug. But if you go to the doctor for heart burn and explain that you ingest a capsule of peppermint essential oil every day, the doctor may be able to match your symptom with the supplement. In this case (which happened to me), cutting down on peppermint oil ended the heart burn.

Finally, consumers need to be cautious when purchasing vitamins and supplements. These products are not regulated the same way over-the-counter drugs are regulated, even though they may be sitting side-by-side on the store shelf. The ingredients for some of these supplemental and “natural” products may come from abroad, where the FDA has limited inspections and jurisdiction. Be suspicious of grandiose marketing claims on product labels. If you are intrigued by a particular supplement, ask your physician about it before you make it part of a regular regimen.

Of course, not all physicians are enthusiastic about natural products, vitamins, and supplementation. If you feel you benefit from these types of products, you may want to find a physician who is more aligned with your way of thinking to give you balanced advice. The truth about vitamins and supplements is somewhere in the middle—they may be helpful but they also can be associated with certain very real risks. The trick is learning to navigate your way around them and integrating them with other prescription drugs and treatments.

Jo Ann LeQuang is a professional writer specializing in medical topics and a Christ-follower who blogs at AWretchLike.Me.