The Dose Makes the Poison: Safe Use of Over-the-Counter Pain Medication

When you twist your ankle or wake up with a headache, it’s easy to reach for pain relieving medications, but what’s in over-the-counter pain medications and how do they affect your physiology? 

There are two major categories of over-the-counter pain relievers: acetaminophen (Tylenol) and non-steroidal anti-inflammatory drugs (NSAIDs). NSAIDs like ibuprofen, aspirin and naproxen work by inhibiting an enzyme called cyclooxygenase (COX), which is normally responsible for creating mediators of pain and inflammation called prostaglandins. However, prostaglandins are also responsible for protecting your kidneys and stomach lining, which is why long-term NSAID use can result in stomach ulcers and kidney damage. The science behind acetaminophen is a little less clear, but it is thought to work directly on the brain to decrease pain and fever. Thus, NSAIDs are best for muscle injuries and joint pain because of their anti-inflammatory properties, while acetaminophen is better for flu-like symptoms due to its fever-reducing effects. Both drug classes are very safe and effective while used as directed, but misuse and overuse pose a significant public health burden. 

Acetaminophen overdose is the leading cause of liver transplantation in the United States and the second leading cause worldwide. It results in 500 deaths each year, fifty percent of which are accidental. Meanwhile, use of NSAIDs is a common cause of acute kidney injury and peptic ulcer disease, especially among older adults who tend to use them chronically for longstanding issues such as osteoarthritis. But why are drugs that are so widely used causing so many problems? One explanation is the increased prevalence of combination drugs with multiple active ingredients and “extra strength” formulations with higher doses of the active ingredient. Both of these factors make it harder for people to keep track of what drugs they are taking and how much. 

A drug’s active ingredient is the ingredient that creates the drug’s desired effect, whether that’s relieving your pain, itch, or allergies. This is in contrast to other ingredients which may just serve to package, color, or flavor the drug. Many different drugs can have the same active ingredient. For example, Advil and Motrin both contain ibuprofen. Confusion arises when drugs have multiple different active ingredients like the popular migraine medication Excedrin, which contains acetaminophen, aspirin, and caffeine. People taking Excedrin might not realize they’re taking both acetaminophen and an NSAID, making it easy to go over the recommended safety limit of 4000 milligrams of acetaminophen a day if they’re also taking other drugs. Just imagine a patient who takes Excedrin for their migraines and Tylenol for their arthritis, not realizing that both of these medications contain acetaminophen! Another potential pitfall is “extra strength” formulations of common drugs. Extra Strength Tylenol contains 500 milligrams of acetaminophen per tablet while the regular version only contains 350 milligrams. Because not all tablets are created equal, it’s easy for people who are simply counting the number of pills they’ve taken to accidentally take more acetaminophen than intended.

It is also important to be aware of potential interactions between medications. Taking acetaminophen with alcohol or certain other medications, such as blood thinners, can increase the risk of liver damage. Always check with a healthcare provider or pharmacist before combining medications. 

Just because drugs are common and familiar does not mean they are without risk. It’s crucial to stay aware of what drugs you’re taking by reading the ingredients list and dosage on all your medications. Remember to be aware of potential interactions, and consult with a healthcare provider if you have any questions or concerns. Most importantly, approach new medications with an attitude of caution, not fear. When used according to established guidelines and only when needed, over-the-counter drugs can (literally) save you a lot of pain!

Written by Smrithi Upadhyayula.

Edited by Devangi Pethani.

References 

1. Agrawal S, Khazaeni B. Acetaminophen Toxicity. [Updated 2023 Jun 9]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2024 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK441917/