Drug interactions

A grab bag of risks

Although over-the-counter drugs taken at the recommended doses rarely cause dangerous side effects in healthy people, they can cause a number of unpleasant symptoms. Those include insomnia and irritability from oral decongestants, constipation from aluminum-containing antacids, diarrhea from magnesium-containing antacids, and indigestion from all pain relievers except acetaminophen (Tylenol). One common side effect – drowsiness from antihistamines, which are contained in all allergy drugs and some cold medications – could be more hazardous. In fact, the maximum recommended dose of some antihistamines can slow reaction time more than the amount of alcohol that would make driving illegal in most states.

The risk of side effects from over-the-counter drugs increases sharply when people take more than they should. For example, swallowing just three times more than the maximum recommended dose of phenylpropanolamine – contained in the oral decongestant Propagest, many cold remedies, and all diet pills – can cause severe and even life-threatening rises in blood pressure. Taking a drug continually without consulting a doctor also multiplies the risk of side effects, such as anemia from chronic use of aspirin or potassium depletion and bowel damage from excessive use of the laxative bisacodyl (Carter’s Little Pills, Dulcolax, Fleet Bisacodyl).

Further, overuse of certain nonprescription drugs can lead to an insidious form of dependency. People who keep taking drugs to relieve headaches or nasal congestion will often get “rebound” symptoms – headaches or congestion worse than the original symptoms – as soon as the drug starts wearing off. That may lead to a vicious cycle of increasingly frequent use of the drug and worsening rebound. Similarly, prolonged use of laxatives can weaken the bowel muscles, causing renewed constipation as soon as the drug is discontinued.

The gravest danger from sustained use of over-the-counter medications is that you might be controlling symptoms while allowing an underlying disease to go untreated. For example, people with stomach pain sometimes take over-the-counter antacids or pain relievers for months without seeing a doctor. Those people may have ulcers or inflammation of the stomach, which can cause serious bleeding; or they may even have stomach cancer.

Over-the-counter drugs can become more dangerous when they’re taken with other medications – an all-too-common practice. According to a recent survey, one out of three people who take antihistamines for allergies take other drugs at the same time. But many common medications can make antihistamines even more sedating than they are when taken alone. The alcohol in a cough syrup such as Comtrex Liquid,Tylenol Cough with Decongestant Liquid, or Vicks Formula 44 Multi-Symptom Cough Medicine can combine with antihistamines to cause excessive drowsiness. In addition, you can get an unexpected double dose of antihistamines by taking an allergy drug along with a cold remedy such as Alka-Seltzer Plus Cold or Contac Severe Cold Formula or with a sleep aid such as Nytol or Sominex, all of which contain antihistamines.

Nonprescription drugs can also change the way other, more vital medications are supposed to work. Taking an antacid to prevent an antibiotic from upset-ting your stomach may also prevent your body from absorbing the medicine, so it never reaches the infection. Conversely, taking a stool-softening laxative may ease constipation caused by the antihypertensive drug verapamil (Isoptin, Calan) – but it may also increase absorption of the drug, leading to an excessive reduction in blood pressure and, in turn, possibly to fainting.

Even ordinary foods can turn a seemingly innocuous drug into a hazardous one. For example, trying to calm your stomach by drinking large quantities of milk and taking antacids containing either calcium, magnesium, or sodium bicarbonate can eventually cause kidney failure.

People with certain chronic diseases are particularly vulnerable to the adverse effects of over-the-counter medications. But by far the most common condition that increases such vulnerability is simply old age.

Older people have more diseases and take more drugs than younger people, which increases all drug-related risks. In addition, the body becomes less efficient at breaking down and eliminating drugs as it ages. As a result, drugs may reach higher levels in the bloodstream and remain there longer. Even at normal levels, many medications have more pronounced effects on the brain and other parts of the aging body. Unfortunately, researchers rarely test new drugs on older people, so the recommended doses are often set too high for them.

Study the table and list the specific risks of the most common drugs given here.

Дата добавления: 2015-01-03