Precautions With Over-the-Counter Medications

Children's bodies metabolize and react to medications differently from the way adults' bodies do. A medication may be used by many people for many years before its hazards to children are discovered. For example, many years passed before researchers confirmed that the risk of Reye syndrome was linked to the use of aspirin in children who had chickenpox or influenza. Doctors and parents alike are often surprised to learn that most over-the-counter (OTC) medications, even those medications with recommended dosages for children, have not been thoroughly tested in children.

Giving a child a correct medication dose can be tricky. Although children's doses are often expressed in terms of age ranges (for example, children aged 2 to 6 or 6 to 12), age is not the best criterion. Children can vary greatly in size within any age range, so experts advise using the child's weight to determine doses of OTC medications.

If the label does not give instructions on how much medication to give the child, a parent should not guess. When in doubt, a parent should consult a pharmacist or doctor. Such consultation may prevent a child from receiving a dangerously high dose of a potentially helpful medication.

Many medications for treating children come in liquid form. Even though the label should give clear guidelines about the dose, a child may be given the wrong dose because the adult in charge uses an ordinary teaspoon. The only kitchen spoons accurate enough to measure liquid medications are measuring spoons. However, a cylindrical measuring spoon is far better for measuring a child's dose, and an oral syringe is preferred for measuring and squirting a precise amount of medication into an infant's mouth. The cap should always be removed from the tip of an oral syringe before use. A child can choke if the cap accidentally ends up in the windpipe. Sometimes, medications intended for treating children come with a measuring device packaged with the product. If so, the device that is in the package should be used to measure the appropriate dose.

Several children's medications are available in more than one form. Adults must read labels carefully every time a new children's medication is used.

Aging changes the speed and ways in which the body processes (metabolizes) medications (see Aging and Medications), and older adults tend to have more diseases and to take more than one medication at a time. For these reasons, older adults may be more likely than younger ones to experience side effects or medication interactions. More and more prescription medication labels specify whether different doses are needed for older adults, but such information is rarely included on over-the-counter (OTC) medication labels.

Many OTC medications are potentially hazardous for older adults. The risk increases when medications are taken regularly at the maximum dose. For example, an older adult who has arthritis may frequently use an analgesic or anti-inflammatory medication, with potentially serious consequences, such as a bleeding peptic ulcer. Such an ulcer is life threatening for an older adult and can occur without warning.

Many antihistamines, such as diphenhydramine, are designated as "sedating" antihistamines and may pose special risks for older adults. Many nighttime pain relief formulas, cough and cold remedies, allergy medications, and sleep aids contain sedating antihistamines. These antihistamines may cause drowsiness or fatigue and may worsen some disorders common among older adults, such as closed-angle glaucoma and an enlarged prostate gland. They can also make a person dizzy or unsteady, leading to falls and broken bones. Antihistamines, particularly at a high dose or in combination with other medications, can sometimes cause blurred vision, light-headedness, dry mouth, difficulty with urination, constipation, and confusion in older adults. Fexofenadine, cetirizine, and loratadine are among the antihistamines considered to be "nonsedating," and they are less likely to cause drowsiness or other side effects.Many antihistamines, such as diphenhydramine, are designated as "sedating" antihistamines and may pose special risks for older adults. Many nighttime pain relief formulas, cough and cold remedies, allergy medications, and sleep aids contain sedating antihistamines. These antihistamines may cause drowsiness or fatigue and may worsen some disorders common among older adults, such as closed-angle glaucoma and an enlarged prostate gland. They can also make a person dizzy or unsteady, leading to falls and broken bones. Antihistamines, particularly at a high dose or in combination with other medications, can sometimes cause blurred vision, light-headedness, dry mouth, difficulty with urination, constipation, and confusion in older adults. Fexofenadine, cetirizine, and loratadine are among the antihistamines considered to be "nonsedating," and they are less likely to cause drowsiness or other side effects.

Older adults may be more susceptible to the possible side effects of antacids. Antacids that contain aluminum are more likely to cause constipation, and antacids that contain magnesium are more likely to cause diarrhea and dehydration.

During visits to the doctor, older adults should mention all OTC products they are taking, including vitamins, minerals, and medicinal herbs. This information helps the doctor evaluate the entire medication regimen and determine whether or not an OTC medication may be responsible for certain symptoms.

Medications can move from a pregnant woman to her fetus (primarily through the placenta—see Medication Delivery During Pregnancy), and medications can be transmitted through breast milk to the baby. Some medications can affect or harm the fetus or baby, so pregnant women and breastfeeding women should consult their doctor or pharmacist before taking any over-the-counter (OTC) medication or medicinal herb. OTC medication labels should be checked because they contain warnings against use during pregnancy and breastfeeding, if applicable.

Certain types of medications are particularly problematic. They include antihistamines (commonly contained in cough and cold remedies, allergy medications, motion sickness medications, and sleep aids) and nonsteroidal anti-inflammatory drugs (NSAIDs). NSAIDs should not be used during the last 3 months of pregnancy unless specified by a doctor, because they may cause problems in the fetus or complications during delivery.

A number of chronic disorders can become worse if an OTC medication is taken inappropriately. Because OTC medications are intended primarily for occasional use by people who are essentially healthy, people who have a chronic or serious disorder or who plan to take an OTC medication every day should consult a health care professional before they purchase OTC products. In these situations, medication use is beyond the normal boundaries of self-care and requires the advice of an expert.

Many people neglect to mention their use of over-the-counter (OTC) medications to their doctor or pharmacist. Medications taken intermittently, such as medications for colds, constipation, or an occasional headache, are mentioned even less often. Health care professionals may not think of asking about use of OTC medications, dietary supplements, or medicinal herbs when they are prescribing or dispensing a prescription. Yet many OTC medications and medicinal herbs can interact adversely with a wide range of medications (see Medication Interactions).

Some of these interactions can be serious, interfering with the effectiveness of a medication or causing side effects. For example, taking aspirin with the anticoagulant warfarin can increase the risk of abnormal bleeding. An antacid containing aluminum or magnesium can reduce the absorption of digoxin, taken for heart disease. Taking a multiple vitamin and mineral supplement can interfere with the action of some prescription medications. For example, the antibiotics tetracycline, ciprofloxacin, or levofloxacin may be ineffective if swallowed with a product that contains calcium, magnesium, or iron.with the anticoagulant warfarin can increase the risk of abnormal bleeding. An antacid containing aluminum or magnesium can reduce the absorption of digoxin, taken for heart disease. Taking a multiple vitamin and mineral supplement can interfere with the action of some prescription medications. For example, the antibiotics tetracycline, ciprofloxacin, or levofloxacin may be ineffective if swallowed with a product that contains calcium, magnesium, or iron.

OTC drug-drug interactions have not been studied systematically. Many serious problems have been discovered accidentally, after side effects or deaths were reported. Even when interaction warnings are printed on the label for OTC medications, the language may be meaningless to most people. For example, the labels of some cold remedies that contain pseudoephedrine caution against using the product with a monoamine oxidase inhibitor (MAOI—used infrequently for depression and certain other medical problems) or during the 2 weeks after discontinuing the MAOI. For the many people who do not know that the antidepressant they are taking is an MAOI (such as phenelzine and tranylcypromine), this important warning is not helpful.OTC drug-drug interactions have not been studied systematically. Many serious problems have been discovered accidentally, after side effects or deaths were reported. Even when interaction warnings are printed on the label for OTC medications, the language may be meaningless to most people. For example, the labels of some cold remedies that contain pseudoephedrine caution against using the product with a monoamine oxidase inhibitor (MAOI—used infrequently for depression and certain other medical problems) or during the 2 weeks after discontinuing the MAOI. For the many people who do not know that the antidepressant they are taking is an MAOI (such as phenelzine and tranylcypromine), this important warning is not helpful.

The best way to reduce the risk of drug-drug interactions is to ask the pharmacist to check for them. Additionally, the doctor should be told about all medications being taken, both prescription and OTC.

Another potential problem is medication overlap. Over-the-counter products used to treat different problems may contain the same active ingredient. Unless people read the labels on everything they take, they can accidentally overdose themselves. For example, a person who takes a sleep aid and a cold remedy, both of which contain diphenhydramine, may take double the dose considered safe. Many products contain acetaminophen. A person who simultaneously takes two different products that contain acetaminophen—one for a headache and another for allergies or sinus problems—may exceed the recommended dose, which can be dangerous.Another potential problem is medication overlap. Over-the-counter products used to treat different problems may contain the same active ingredient. Unless people read the labels on everything they take, they can accidentally overdose themselves. For example, a person who takes a sleep aid and a cold remedy, both of which contain diphenhydramine, may take double the dose considered safe. Many products contain acetaminophen. A person who simultaneously takes two different products that contain acetaminophen—one for a headache and another for allergies or sinus problems—may exceed the recommended dose, which can be dangerous.

The following is an English-language resource that may be useful. Please note that The Manual is not responsible for the content of this resource.

1. OTC Products and Dietary Supplements: A site for reporting adverse events associated with use of over-the-counter (OTC) medications and dietary supplements.