While cold medicines are helpful in relieving many of the symptoms related to the common cold, they can cause a variety of side effects as well. Over-the-counter cold medicines are usually a combination of drugs depending on the symptoms. Each medication can cause a different range of side effects. Consult your physician before taking cold medicines if you suffer from a heart condition, kidney disease, glaucoma, or other medical condition. In addition, cold medicines are not recommended for young children.
Antihistamines in cold medicines relieve itchy and watering eyes, sneezing, a scratchy throat, and a runny nose. While drowsiness is the most common side effect of antihistamines, dizziness, headaches, dry mouth, dry eyes, and feelings of fatigue are also possible. Alcohol consumption while taking antihistamines can increase drowsiness and fatigue.
Decongestants--such as pseudoephedrine or phenylephrine--will help reduce congestion in the sinuses, but they can also increase blood pressure and your heart rate. Restlessness, insomnia, tremors, and anxiety are possible side effects of decongestant drugs as well. According to the Minnesota Poison Control, caffeine consumption can worsen these symptoms.
Cough Suppressants & Expectorants
Dextromethorphan reduces coughing and breaks up mucus in the sinuses. According to FamilyDoctor.org, cough suppressants and expectorants can cause drowsiness, nausea, confusion, and dizziness. Cough suppressants can cause constipation, while expectorants can cause diarrhea. Consult your physician if your cough is chronic or if you are producing yellow or green mucus.
Pain relievers--such as ibuprofen or acetaminophen--will help with the headaches and body aches associated with the common cold. Acetaminophen and ibuprofen are both safe when proper dosing is followed. Acetaminophen is in many different kinds of medications so be watchful of the amount you are taking throughout the day. If you are prone to stomach problems, take ibuprofen with a meal since it can cause stomach discomfort.
Sleeping aids such as diphenhydramine will assist you in falling asleep at night when you have a cold. Diphenhydramine can also leave you feeling groggy the next day and mildly disoriented. Dry mouth, urinary retention and decreased respiratory secretions are also side effects of sleeping aids in cold medicines.
According to the Minnesota Poison Control System, the drugs in many cold medicines can interact negatively with other medications. Monoamine oxidase inhibitors--such as Marplan, Nardil and Parnate--are a class of antidepressants that will cause a drug-drug interaction, in which side effects can be worsened. Selective serotonin reuptake inhibitors--such as Celexa, Prozac and Paxil--will also interact with cold medicines. Consult your physician if you have any concerns about these medications or any other drugs that you may be taking.