Adverse drug effects send 4.5 million Americans to the doctor’s office or emergency room (ER) each year. Tens of millions of milder reactions, such as drowsiness, sleeplessness and nausea, also occur.

Cold medications are among the drugs that sometimes can be more harmful than helpful. Your best defense is to always be wary when reaching for any over-the-counter (OTC) medication because they are not necessarily safe.

Here are some common medications, used to treat colds that come with hazards.

Acetaminophen and liver damage

Each year, about 78,000 people end up in the ER for acetaminophen toxicity, which can lead to severe liver damage. Safely used, acetaminophen relieves pain and fever from colds and flu. However, the number of drugs available containing this ingredient make it easy to ingest too much.

Acetaminophen is found in more than 600 different medications which makes it the most common drug ingredient in America. Here’s a short list of some over-the-counter cold and flu remedies containing acetaminophen: Alka-Seltzer Plus Liquid Gels, Benadryl, Dimetapp, Excedrin, Sudafed, Theraflu, Tylenol, Vicks, Dayquil and Nyquil.

Getting too much acetaminophen can result in liver damage. In fact, acetaminophen is the No. 1 drug associated with liver injury. Initial symptoms may mimic the flu and include nausea, vomiting, stomach pain and loss of appetite. Later, symptoms include dark urine and a pain on the upper right side of the body. Get immediate help if you suspect acetaminophen overdose.

What to do:

Never exceed 4,000 mg./day, according to the National Institutes of Health. Read the drug warnings carefully. Don’t combine acetaminophen with alcohol. Take the lowest possible dose for relief. Read all drug labels carefully because many drugs, such as cold meds, contain acetaminophen.

Decongestants

Decongestants, used to relieve nasal congestion, can cause blood pressure to rise and interfere with the effectiveness of blood pressure medications.

What to do:

If you have high blood pressure, consult with a doctor before taking decongestants.

Ibuprofen

NSAIDs or nonsteroidal anti-inflammatory drugs are used by cold/flu sufferers to relieve body aches, pains and fever. However, these drugs can produce severe allergic reactions in people allergic to aspirin, and chronic use can result in peptic ulcers and kidney damage.

What to do:

Avoid using these drugs if you are allergic to aspirin or have stomach problems.