Over-the-counter pain relievers: Play it safe

Don’t let the ease of buying pain medications without a prescription lull you into thinking they’re trouble-free.

It used to be pretty simple: If you had pain, you took aspirin. But thanks to advances in understanding how we experience pain and the mechanisms for relieving it, we now have many more drug options. For most mild to moderate pain, the first choice is usually an over-the-counter pain reliever (analgesic). Most fall into one of two categories, nonsteroidal anti-inflammatory drugs (NSAIDs) or acetaminophen.

Since these drugs are widely available and require no prescription, it’s tempting to assume they’re 100% safe. But they have side effects, just as prescription drugs and alternative or complementary preparations do, especially when taken in heavy doses for extended periods. Over-the-counter pain relievers can also interact with other drugs, dietary supplements, and alcohol. Moreover, they contain the same active ingredients found in many combination nonprescription and prescription drugs, such as those for cold and flu relief and allergies. Consequently, if you’re taking several medications, you may be getting more of a particular analgesic than you realize.

Take an over-the-counter medicine only at the dose and frequency recommended, or as instructed by your clinician. Also, learn as much as you can about the pain relievers you take and their interactions. The information below will give you a start.

What do NSAIDs do?
Nonsteroidal anti-inflammatory drugs reduce pain, inflammation, and fever.

How do they work? NSAIDs inhibit cyclooxygenase (COX), an enzyme that spurs the production of hormone-like substances called prostaglandins. One form of the enzyme, COX-2, is behind the prostaglandins that cause fever, inflammation, and pain. By blocking COX-2, NSAIDs prevent or reduce these symptoms. The downside is that they also block COX-1. COX-1 is responsible for prostaglandins that protect the stomach lining, regulate blood flow to the kidneys, and initiate blood clotting.

What can go wrong. Stomach inflammation, peptic ulcers, and intestinal bleeding are major hazards for NSAID users. People who take high doses for a long time are at greater risk, as are older people and those infected with the bacterium Helicobacter pylori, the chief cause of stomach ulcers. NSAIDs also slightly increase the risk for hemorrhagic stroke (bleeding in the brain). Overuse may cause ringing in the ears, dizziness, kidney and liver problems, or high blood pressure. Fortunately, many of these side effects are uncommon and go away when you stop taking the NSAID.

What to do. If your blood pressure is not under control, don’t take NSAIDs. They can worsen hypertension and reduce the effectiveness of ACE inhibitors, medications used to lower blood pressure. Do not take an NSAID before discussing it with your clinician if you’re taking warfarin (Coumadin) or another blood-thinning agent, if you’re pregnant, or if you have a stomach or peptic ulcer, gastrointestinal bleeding, nasal polyps, kidney or liver disease, anemia, or asthma. Up to 20% of people with asthma are sensitive to aspirin and other NSAIDs.

NSAIDs can increase the risk of bleeding anywhere in the body, so you should stop taking them at least a week before surgery, including dental surgery and procedures such as colonoscopy. If you need to use NSAIDs for an extended period, ask your clinician about using a proton pump inhibitor (HWHW, May 2004) to reduce your risk of stomach ulcers. To avoid stomach upset, take NSAIDs with food or after a meal.

What about acetaminophen?
Acetaminophen relieves pain and fever by a somewhat different mechanism.

How does it work? Acetaminophen alters prostaglandin production, but only in the central nervous system (the spinal cord and brain), where it helps raise the pain threshold and quell fever. It doesn’t relieve inflammation, but for the same reason, it doesn’t cause the bleeding and clotting problems associated with NSAID use. Clinicians often recommend acetaminophen when inflammation isn’t involved. But it has side effects of its own.

What can go wrong. Acetaminophen is metabolized by enzymes in the liver. Taking too much can lead to a buildup of a toxic metabolite and liver damage. Some people, such as heavy users of alcohol, are more susceptible to this type of harm. You can get an overdose by taking two or more acetaminophen-containing products at the same time, or by taking doses at short intervals.

What to do. Don’t take acetaminophen if you regularly have more than one drink of alcohol per day. Check the labels of all your medications to make sure you’re not exceeding the maximum recommended dose of acetaminophen — 4,000 mg per day, for people with no liver problems.

Nonprescription pain relievers and some common brand names Nonsteroidal anti-inflammatory drugs (NSAIDs) aspirin (acetylsalicylic acid): Ascriptin, Aspergum, Bayer, Bufferin, Ecotrin, St. Joseph’s ibuprofen: Advil, Excedrin IB, Motrin, Motrin IB, Nuprin naproxen sodium: Aleve, Anaprox, Naprosyn ketoprofen: Orudis Acetaminophen Anacin-3, Datril, Panadol, Phenaphen, Tylenol

Combination drugs
Some NSAID and acetaminophen products, as well as cold, sinus, and allergy remedies, contain a combination of pain relievers (see “Active ingredients in some combination over-the-counter pain products”). The idea is that several active ingredients combined at low to moderate doses can increase overall effectiveness while minimizing the risk of side effects. A common ingredient of these combination drugs is caffeine. Caffeine boosts the effect of pain relievers and may have its own analgesic effect. It’s also a vasoconstrictor, which can help relieve migraine headaches, and a central nervous system stimulant that may help to lift mood.

Combined ingredients sometimes cause problems, though. Regular and long-term use of painkillers that combine analgesics can damage the kidneys.

Avoid mixing
If you don’t fall into a specific at-risk group, using an over-the-counter pain reliever as directed on the package is generally safe. But there’s potential for trouble if you’re also taking certain other products.

Prescription pain drugs. Many prescription painkillers, such as Endocet, Darvocet, and Vicodin, contain acetaminophen. Others, such as Celebrex, Vioxx, Percodan, and Feldene, contain NSAIDs. To avoid getting too much acetaminophen or an NSAID, don’t take both a prescription and an over-the-counter painkiller without checking with your clinician. Also, be aware of less obvious sources of acetaminophen and NSAIDs, such as Alka-Seltzer Plus, BC Powders, Dristan cold and sinus products, Contac, TheraFlu, and Sudafed. If you’re unsure about safe levels of acetaminophen or an NSAID, talk to your clinician or pharmacist.

The American Academy of Family Physicians has prepared a chart of prescription drugs containing acetaminophen and NSAIDs and the nonprescription products you should avoid while taking them. It’s available at www.familydoctor.org/otc/knowmeds.html.

Drug interactions. NSAIDs can interact with ACE inhibitors, anticoagulants, beta blockers, lithium, and methotrexate. Aspirin also interacts with anticonvulsants, corticosteroids, insulin, and sulfa antibiotics. If you’re taking any of these prescription medications, check with your clinician before using NSAIDs.

Herb-drug interactions. Garlic, ginger, feverfew, ginkgo, and ginseng can thin your blood. Don’t take them if you’re already taking an NSAID.
Supplement-drug interactions. NSAIDs may interfere with folate (folic acid) absorption, so you may want to increase your intake of dietary folate or take a folic acid supplement if you’re using an NSAID regularly. Vitamin E may boost the anti-clotting effect of aspirin.

Supplement-drug interactions. NSAIDs may interfere with folate (folic acid) absorption, so you may want to increase your intake of dietary folate or take a folic acid supplement if you’re using an NSAID regularly. Vitamin E may boost the anti-clotting effect of aspirin.