Over-the-Counter Drugs - Reactions with Other Drugs or Substances

Reactions with Other Drugs or Substances

Mixing OTC and prescription drugs can have many adverse reactions, or negative side effects, depending on the medications being combined, the condition being treated, and the person taking the drugs. Certain combinations can affect blood pressure and breathing, alter one's heartbeat or heart rate, cause drowsiness or dizziness, and lead to nausea, diarrhea, and various other complications. In cases of pregnancy, many OTC and prescription drugs not only work on the mother, but can affect the baby as well.

As such, people should always check with their doctor or pharmacist before starting any new medications and/or combining drugs. In addition, drug manufacturers include various warnings about drug interactions. The warnings are listed on the drug's box, bottle, or on paper instructions inside the package. Also, many pharmacies provide information for customers noting possible drug interactions. Before taking any drug, it's important to read all the warnings. People should also be aware of any effects associated with combining OTC drugs with alcohol, caffeinated beverages, herbal and dietary supplements, and various illegal drugs.

Anxiety, Allergy, and Cold/Flu Remedies

Anyone taking a prescription medication, particularly one for anxiety or depression, should ask a doctor before taking any OTC allergy preparation. Pregnant women and nursing mothers should avoid OTC allergy medicines altogether.

Manufacturers' labels on multi-symptom cold and flu medicines warn users not to drink alcohol—and sometimes even beverages containing caffeine—while taking these medicines. Alcohol can cause dizziness and disorientation, and it also dehydrates the body, possibly causing cold symptoms to last longer. In addition, patients taking prescription medicines should consult a doctor before adding cold and flu remedies to their mix of drugs. Substances such as diphenhydramine, dextromethorphan, and caffeine can react badly with prescription medicines for depression, anxiety, and liver problems.

Dextromethorphan may increase the effects of other drugs that cause drowsiness, including antidepressants, alcohol, antihistamines, sedativesA drug used to treat anxiety and calm people down., pain relievers, anxiety medicines, seizure medicines, and muscle relaxants. Likewise, chlorpheniramine maleate and pseudo-ephedrine hydrochloride should not be mixed with other medications for colds or allergies, or with any type of tranquilizerDrugs such as Valium and Librium that treat anxiety; also called benzodiazepines (pronounced ben-zoh-die-AZ-uhpeens)., sedative, or sleeping pill.

People with diabetes or allergies to artificial sweeteners should check the ingredients listed on any sore throat medication, cough syrup, or cough drop, since many of these substances contain some form of sugar or sweetener. Some cough syrups also contain alcohol.

Motion Sickness, Diet Pills, and Sleep Aids

Mixing motion sickness medicines with alcohol, sedatives, tranquilizers, or other antihistamines can cause extreme drowsiness.

Diet pills should not be combined with antihistamines, certain prescription antidepressants, coffee or caffeinated soft drinks, or heart medications. Mixing diet pills with other drugs and substances can lead to high blood pressure and an irregular or rapid heartbeat.

Sleep aids should not be combined with alcohol, caffeine, or prescription medications for anxiety or depression. For OTC sleeping pills that contain the active ingredient diphenhydramine, use of Benadryl or any other diphenhydramine-containing medication should be stopped—even if it is only applied to the skin.

Stimulants and Laxatives

OTC stimulants should not be taken with coffee, tea, or other beverages containing caffeine because caffeine is a stimulant too.

Some laxatives can interfere with the absorption of other medicines. Anyone taking a prescription medication, or even an OTC preparation, should check with a doctor before using a laxative.