The Most Common Side Effects I See From OTC Meds—and How to Avoid Them | The Survival Doctor

by James Hubbard, MD, MPH

It’s disaster time and you have a problem. Maybe pain from an injury or headache or misery from indigestion or a cold. You delve into your stash of over-the-counter medications you’ve saved for times just like this and take one you’ve taken many times before. Two hours later, you have a rash or stomach pain or some other odd new problem. Is it related to the medicine? I mean, you’ve taken it so many times in the past.

Remember this: Any medication, herb, supplement, oil, or food that can work on your body in a positive way has the potential to affect it in a negative way as well. No matter how many times you’ve taken something in the past, it can give you just about any side effect you can think of at any given time, and that includes an allergic reaction.

Some side effects are more serious or debilitating than others. If you’re at increased risk for a bad one, think about whether the medication’s benefits outweigh its potential risks, knowing you couldn’t get expert help if you needed it.

Below are my best tips to avoid some of the more common side effects with over-the-counter medications I’ve encountered in patients over the years.

1. Aspirin

Aspirin has been around forever and is great for inflammation; pain; and, in some people, helping prevent heart attacks and strokes.

If you:

  • Have stomach issues such as ulcers, avoid. Aspirin causes stomach irritation.
  • Drink alcohol, never drink it with aspirin. This increases your risk for stomach irritation.
  • Have a bleeding disorder or take the prescription blood thinner warfarin (Coumadin), remember that aspirin increases your risk for bleeding. (It’s amazing how well it prevents the initial phases of clotting. Clotting has several phases, but it starts with the platelets becoming sticky. Aspirin decreases their stickiness. Many a time after someone’s taken aspirin, I’ve had to apply pressure to even a small nick for five or 10 minutes to give the blood time enough to go into its other phases of clotting.)
  • Have an injury that could be causing internal bleeding, like head trauma, stay away from aspirin for pain.
Herbs and Supplements That Can Cause Bleeding

Just for good measure, here are some herbs and supplements that, like aspirin and NSAIDs, can cause bleeding not to clot right away. Especially be wary if you’re taking a prescription blood thinner.

  • Chamomile
  • Feverfew
  • Fish oil
  • Garlic
  • Ginger
  • Ginkgo
  • Ginseng
  • Vitamin E

NSAIDs, such as ibuprofen (Advil, Midol, Motrin) and naproxen (Aleve, Anaprox, Naproxyn), are for pain and inflammation.

If you:

  • Have stomach issues, know that NSAIDs can cause stomach irritation though they may be tolerated better than aspirin.
  • Drink alcohol, never drink it with NSAIDs. This increases your risk for stomach irritation.
  • Take warfarin, NSAIDs may interact with it, so don’t take an NSAID unless you’ve OK’d it through your doctor.
  • Have a bleeding disorder or an injury that could be causing internal bleeding, don’t take because NSAIDs can affect clotting.
  • Have water retention, know that NSAIDs may cause more swelling.
  • Have high blood pressure, be careful because NSAIDs can increase it.
  • Have congestive heart failure, avoid NSAIDs, which can make it worse.
3. Acetaminophen

Acetaminophen is commonly known as Tylenol, but it’s also in a lot of combination over-the-counter medicines, including many cold medicines. Read labels carefully so you don’t mix two meds that contain it and end up overdosing on it.

If you:

  • Feel miserable, don’t be tempted to take more of this than the label directs you to. A dose just a little above the recommended one can lead to liver damage.
  • Drink alcohol, don’t drink with acetaminophen because of the potential for liver damage.
  • Take warfarin, acetaminophen may interact, so don’t take it unless you talk to your doctor.
Check the Label

Always check the ingredients of whatever you’re taking. Many antihistamines and decongestants, for example, are often in combination cold or pain medicines.

4. Antihistamines

Antihistamines are often used for allergies and are found in some cold and sleep medicines. Examples are diphenhydramine (Benadryl), chlorpheniramine (Chlor-Trimeton), dimenhydrinate (Dramamine), and meclizine (Dramamine Less Drowsy). And then there are the nonsedating types, which still can cause drowsiness in some people: loratadine (Claritin), cetirizine (Zyrtec), and fexofenadine (Allegra).

If you:

  • Are in a stressful situation (likely during a disaster), keep in mind that though drowsiness is common with these meds, they can actually make some people agitated instead.
  • Have urinary issues, know that antihistamines can relax the muscles in the bladder so much it can be difficult to urinate. This is particularly true in men with large prostates (benign prostatic hyperplasia, or BPH)—to the point where it can be impossible to urinate until the medicine wears off.
5. Decongestants

These can decrease swelling in the nostrils due to colds. They do it by constricting blood vessels. Pseudoephedrine (Sudafed Congestion) and phenylephrine (PediaCare Children’s Decongestant) are the common ones. Like antihistamines, decongestants are often found in cold medicines in combination with other medicines.

If you have:

  • Heart problems, consider that decongestants can raise blood pressure and cause heart palpitations.
  • Urinary issues, know that, like the antihistamines, decongestants can cause trouble urinating. But they do it in another way—by constricting the muscles so tightly around to the bladder opening that the urine can’t get out.
6. Nasal Spray Decongestants

These work like the oral decongestants and can give the same side effects, but because they’re sprayed locally to the nose, the side effects are less frequent.

If you have:

  • High blood pressure or BPH, be careful.
  • Long-term sinus problems, take a break on the OTC decongestant spray every few days. It can cause a rebound in swelling: After the medicine works and wears off, there’s more nasal congestion than before it was used. And after three to five days of nonstop use, it can damage the nasal membranes so that even after the cold or allergy is gone, the nasal swelling continues.
7. Bismuth Subsalicylate

This is best known by its brand name of Pepto-Bismol.

If you have:

  • Problems with aspirin, don’t use since it’s related.
  • A possibility of internal bleeding, consider avoiding this medicine because it can cause black bowel movements. This is not really harmful, but black bowel movements can also be a sign of internal bleeding, so it’s best not to be guessing at the cause during a survival situation. (This medicine can also cause a black tongue coating, by the way—also not harmful.)
8. Calcium

This mineral is found in some supplements and multivitamins, and is the main ingredient in antacids such as Tums and Rolaids.

If you have

  • Issues with bowel movements, know that calcium can cause severe constipation.
9. Caladryl

Caladryl lotion, which contains diphenhydramine (an antihistamine sold in oral form as Benadryl and other brand names) and calamine, is used to relieve the itch from rashes.

If you:

  • Are stocking meds for a disaster situation, when you won’t want to take risks with your comfort, consider stocking Calamine Plain instead. This is just calamine—no diphenhydramine—so it doesn’t carry the risk of causing the local allergic reaction that Caladryl can, which results in even more itching.
Common Side Effects, Listed

Click here for a list of some common side effects in 10 popular meds.

10. Antibiotic Ointments

These are used on skin wounds to prevent infection. Any lotion, cream, or ointment can cause allergic reaction or irritated skin in anyone.

If you:

  • Notice an increased itching or redness after using the ointment, consider stopping it or switching to another type. The ingredient neomycin seems to be the most common culprit, so if it’s the one you’re using, switch to one without it, or just start with one without neomycin in the first place.


What about you? Have you had any of these common side effects or others you can share?


Disclaimer: These are not the only side effects these medications cause. Read the medicine’s package insert, including warnings and interactions, before taking.