You’re health-savvy enough to know that it’s important to tell your doctor about any dietary or herbal supplements you take—because some supplements can cause big problems in people who take certain medications, and vice versa.

But do you also tell your dentist about all the supplements you take? You should…for the exact same reason. After all, oral-health-care providers—dentists, periodontists, orthodontists, endodontists and oral surgeons—all may prescribe or administer medications before, during and after dental procedures.

And certain supplements are especially likely to cause problems if combined with the particular types of medications dental patients most often are given. Fortunately, there’s an easy way to avoid this, a new study suggests.

RISKY COMBINATIONS

The study that caught my eye was led by Mark Donaldson, PharmD, a clinical professor at the University of Montana’s Skaggs School of Pharmacy in Missoula. He reviewed various drug-interaction databases looking for evidence of interactions between supplements and drugs that are commonly used in dental practice, so I called him for more details. Here’s what he discovered about…

Ginkgo biloba and evening primrose. These herbs can reduce your blood’s ability to clot, possibly leading to excessive bleeding during and/or after your dental procedure—particularly if you also take another anticoagulant, such as aspirin or ibuprofen (Advil).

Recommended: Ginkgo’s half-life (the time it takes for the substance’s concentration in your body to be reduced by half) is about seven hours, and it takes about four half-lives for 90% of the drug to be eliminated from your system—so you should stop taking ginkgo at least 28 hours before a dental appointment to reduce your risk for excessive bleeding. Evening primrose doesn’t linger in the body quite as long, so stopping it 24 hours before your appointment should give enough time to clear it from your body.

St. John’s wort. The most potential interactions are found with this herb, which often is used to help reduce anxiety, ease depression or aid sleep. St. John’s wort can increase your sensitivity to sunlight, potentially leading to severe sunburn—and its likelihood of doing so is increased when it is combined with other drugs that are frequently administered or recommended by dentists. These include ibuprofen…the antibiotics azithromycin, doxycycline and tetracycline…and the antihistamine diphenhydramine (Benadryl), given in the event of an allergic reaction or simply during the allergy season.

St. John’s wort also can interfere with the metabolism of antianxiety benzodiazepines such as alprazolam (Xanax), diazepam (Valium) and lorazepam (Ativan)…sedatives such as zaleplon (Sonata) and zolpidem (Ambien)…the antibiotics clarithromycin, clindamycin, erythromycin, doxycycline and tetracycline…and the anti-inflammatory drugs prednisone and dexamethasone (Decadron). All these drugs can be rendered less effective when combined with St. John’s wort.

Finally, narcotics such as codeine, hydrocodone (Vicodin) and oxycodone (OxyContin) can become even more intoxicating when taken with St. John’s wort. This can lead to sleepiness, lethargy and dizziness in some patients, greatly reducing their ability to function normally for the rest of the day or even longer, Dr. Donaldson cautioned.

Best: The half-life of St. John’s wort is up to 25 hours, so discontinue it four days before your dental appointment. Unlike with antidepressants, which must be tapered off gradually, there is no risk in abruptly stopping St. John’s wort because the herb’s long half-life basically makes it “self-tapering,” Dr. Donaldson said.

Valerian. This herb has mild sedative effects—and that’s where the real problems can occur. Dentists may prescribe benzodiazepine drugs to help anxious patients relax in the chair…or they may prescribe strong painkillers containing codeine for after a procedure. “Any time you use something that depresses the central nervous system in combination with another drug that does the same, they are going to have an additive effect. And if the two substances work by different mechanisms, they could produce a synergistic effect, so that the end result is even greater than the sum of the substances’ individual effects,” Dr. Donaldson said. For some patients, this can lead to significant sleepiness, lethargy and dizziness that can persist into the next day.

Important: Valerian use should be stopped at least 24 hours before your dental appointment.

Calcium and magnesium. Certain antibiotics commonly used in dentistry, particularly doxycycline and tetracycline, bind to these minerals—which means that the antibiotic won’t be properly absorbed, compromising your ability to fight off infection.

What to do: If you supplement with either or both of these minerals and your dentist prescribes antibiotics, allow at least two hours between the time you take the drug and the time you take the supplement. Remember that these minerals often are found in dairy products, multivitamins and antacids, so the same guidelines would apply, Dr. Donaldson noted.

Fish oil or another omega-3–rich oil. These very popular supplements weren’t included in the review, so I asked Dr. Donaldson if there were any concerns. He said, “One potential issue is that fish oil might interfere with the absorption of drugs. However, since none of the drugs commonly used in dentistry that we reviewed are particularly fat-soluble, the fish oil should not markedly increase or decrease the effectiveness of those drugs. However, high doses of fish oil can have anticlotting effects, so there could be a problem with bleeding, particularly if the patient also is taking aspirin.”

What to do: “If you normally take more than three grams a day of omega-3–rich oil, consider reducing your daily dose to three grams at least 24 hours ahead of your dental appointment. The day after your appointment, you can return to your usual higher dose,” Dr. Donaldson said.

SAFEST BETS

Certain medications used by dentists have better safety profiles than others in the same class, so if your dentist is unsure about a potential interaction, it’s best to opt for the drug with the least chance of becoming half of a bad combination, Dr. Donaldson said. Talk to your dentist about the options for…

Pain relief. Acetaminophen (Tylenol) is probably the safest pain reliever for most people who take supplements, Dr. Donaldson said, because it’s not associated with major drug-supplement interactions (though at high doses or if taken with alcohol it can damage the liver). Do not exceed the maximum dosage listed on the product label.

If acetaminophen alone does not provide sufficient relief (for instance, after serious drilling or other major dental work), the best bet is to combine acetaminophen with a nonsteroidal anti-inflammatory medication, such as ibuprofen. As always, your goal should be to use the lowest possible dose for the shortest period of time necessary to achieve the needed effect.

Antibiotics. Safest for supplement users are usually amoxicillin, cephalexin, metronidazole and penicillin. If your dentist says that you need an antibiotic, ask whether one of these four would be appropriate.

Sedatives. For dental patients who need a sedative or antianxiety medication, nitrous oxide gas is typically a safe choice, Dr. Donaldson said, because it is not metabolized by the body. Instead it is inhaled, usually through a nasal mask, and diffused through the lungs before entering the brain and triggering relaxation. This happens quickly, typically within three deep breaths…and the nitrous oxide exits the system within minutes once the gas is turned off. Its effect is easily modified, so if you’re already taking valerian, for example, your dentist can simply “dial down” the concentration of nitrous oxide you inhale.

OPEN WIDE AND SPEAK UP

Considering that more than one-third of all Americans now take supplements, all health-care providers should be asking every patient about their use. But according to a recent survey by AARP and the National Center for Complementary and Alternative Medicine (a part of the National Institutes of Health), 67% of the adults surveyed did not speak with their health-care providers about any supplement use. Of those who did, the majority said that they themselves—and not their health-care providers—brought up the topic.

Takeaway message: If your dentist doesn’t ask you about all of the drugs you use, including over-the-counter medications and supplements, take the initiative and bring up the subject. If your dentist is not well-versed in drug-supplement interactions, show him this article—he may learn quite a bit!