Unexpected Side Effects

Lauren Cahill, PharmD/MBA Candidate 2007
Shenandoah University
Prepared during Consumer Health Information Corporation Clerkship
McLean, VA

Side effects are common to all medications. A side effect can be a headache or an upset stomach that goes away within a few days once your body becomes used to the drug. Other medications have side effects that may not go away.

How do you know what side effects are common to your medication? When you fill a prescription, the pharmacy provides a patient information pamphlet that lists all the possible side effects of that medication. It is important to read this information to understand what side effects you may experience. Not all side effects will occur in each patient. People who do not read the medication information handout could be putting themselves at risk for an unexpected side effect.

Memory Loss

“A patient remembers nothing after taking a sleeping pill before bed – until he awoke in jail to learn he had left his bed and gone for a drive, smashed into a parked van and driven away before crashing into a tree.”

Imagine that you took your sleeping pill and during the time you thought you were sleeping you were actually driving your car, eating the entire kitchen, or acting out superhero powers. This may seem impossible. There have been 48 cases of these bizarre behaviors last year all linked to a popular prescription sleeping pill. People have nighttime adventures with no memory of their behavior. Many of these cases involved patients drinking alcohol before taking the sleeping pill. To avoid abnormal nighttime behaviors, it is important to follow your sleeping pill directions. The prescription warning label states: not drink alcohol while taking this medication and to take the medication right before bed.¹

Diarrhea

“Have you ever taken an antibiotic for an infection and within days you get diarrhea?”

You are not alone. 20% of people taking antibiotics develop diarrhea either while taking the antibiotic or shortly after finishing the medication. The diarrhea is usually mild and will clear up in a few days.

Diarrhea occurs when the antibiotic kills the body’s natural bacteria along with the harmful bacteria. When the body’s natural bacteria are weakened, the body cannot protect itself as well and harmful bacteria begins to grow causing diarrhea. Call you doctor if the diarrhea does not go away or becomes severe. This can help prevent a more serious adverse effect.²

Uncontrollable Body Movements

“My mouth, arms, legs, and head keep moving. I cannot control them.”

Uncontrollable body movements can occur any time during treatment with antipsychotic medications that are used to treat schizophrenia and bipolar disorder. Some people may develop tilting their head to one side, jaw spasms, uncontrollable tongue movements, and muscle stiffness or shaking of the arms and legs. Some of the newer anti-psychotic medications do not cause this adverse effect as much. Before you start taking anti-psychotic medications, make sure you read the medication instruction sheet that comes with the medicine and tell your doctor if you develop any strange movements. It is important to catch these side effects early so they do not become permanent.³

Unexplained Muscle Weakness and Achilles tendon Pain

“All a sudden your muscles are weak and sore. You have not excised or participated in any activities that would strain your muscle. Is it just old age causing this muscle pain in your daily activities?”

The culprit may be your cholesterol medication. “Statins” are a class of medication commonly used to help lower high cholesterol. “Statins” can cause unexplained muscle pain, weakness, and/or tenderness in some people. This is a serious side effect involving the actual breakdown of muscle tissue. It is very important that you tell your doctor if you develop any unexplained muscle pain or weakness while taking your high cholesterol medication.

“Statins” can cause Achilles heel pain. Many people ignore this pain considering it pulled a muscle. Your doctor will want to perform some tests to determine if your muscle pain is normal or if you might be developing a more serious side effect.^4,5

Suicidal Thoughts

“Antidepressant medication is supposed to be the “happy” pill. Would you ever think that they could lead to suicide?”

All antidepressant medications increase the risk of suicide in children and adolescents. The Food and Drug Administration (FDA) requires all antidepressants to be distributed with a Patient Medication Guide (MedGuide) to advise patients on the risks and precautions to be taken. Read the MedGuide and inform your doctor of any changes you see in your child while taking antidepressant medication. Talk to your child about suicidal thoughts so they can understand the seriousness of the matter.⁶

Cough

“Is it possible for your medication to cause you to cough?”

How many people would ever think that their cough could be due to their medicines? There is a class of medicines used in the treatment of high blood pressure, heart failure, and in diabetes to protect the kidneys called angiotensin-converting enzyme inhibitors (ACE-I). A common side effect that can occur any time during the use of these medications is a dry cough without mucous. This side effect is more bothersome then dangerous. The cough usually goes away once the medication is stopped. Do not stop your medication without talking to your doctor.

Many patients would consider this to be the start of a cold and might self-treat the cough with over-the-counter medications. Cough medications will not relieve this type of cough. You must to tell your doctor if you develop a cough while taking an ACE-I medicine. Your doctor may need to change your medication.⁷

Dry Mouth and Blurry Vision

“Is your mouth dry and your vision blurry when taking certain medications?”

Many drugs commonly used to treat depression, allergies, psychotic states, and Parkinson’s disease have side effects due their anticholinergic properties. Anticholinergic medications block acetylcholine, a substance that is responsible for many central nervous system activities. When this substance is blocked, the body produces less saliva causing dry mouth. There is also less tear production in the eyes causing dry eyes leading to blurred vision. Other side effects can include constipation, difficulty urinating, and confusion. Drink plenty of fluids while taking your medication. Sucking on hard candy may help relieve dry mouth.⁸

Constipation

“I have not pooped in days.”

Narcotics relieve severe pain and cause constipation in most people because the drug slows down the rate that food moves through the intestinal tract. The slowed rate of food passage causes the body to draw water out of the stool. The result is that the stool becomes hard and constipation results. Most physicians will prescribe a stool softener to help maintain normal bowel movements. Constipation can also be relieved through lifestyle changes such as eating more fiber and drinking plenty of fluids. ⁹

Excessive Gambling and Compulsive Behaviors

“A 52-year-old man taking a commonly prescribed Parkinson’s drug began to wager compulsively and lost $100,000 in casinos.”

Parkinson’s medications work by increasing the neurotransmitter dopamine in the brain to help control the physical symptoms of the disease. Dopamine also affects many other brain functions such as the ability to experience pleasure and pain. Dopamine is also thought to play a role in addictive behavior. Study trial evidence consistently links increased dopamine to increased compulsive behavior. Compulsive behavior can include excessive gambling, unnecessary shopping sprees, and addiction to sexual activity. If you know that this side effect could occur with your medicine, make sure you ask your family to help you. If changes in your behavior occur, contact your physician.¹⁰

Be prepared to handle side effects. Whenever you start taking a new medicine, read the patient medication instructions that come with the medicine. If you have any questions, ask your doctor or pharmacist to explain them to you. Keep the instruction sheet on hand so that you can refer to it at a later date. Don’t let side effects surprise you.

If you think you might be developing a side effect, call your doctor. It is important to note any changes that your body experiences while taking your medication. If you are unable to contact your doctor right away call your pharmacy with questions.

References

1. Morgernthaler TI, Sibler MH. Amnestic sleep-related eating disorder associated with zolpidem. Sleep Medicine. 2002;3(4):323-27.
2. Gleckman RA, Borrega F. Adverse reactions of antibiotics. Postgraduate Medicine. 1997;101(4):97-110.
3. Casey DE. Pathophysiology of antipsychotic drug-induced movement disorders. J Clinical Psychiatry. 2004;65(9):25-8.
4. Chazerain P, Hayem G, Hamza S, et al. Four cases of tendinopathy in patients on statin therapy. Joint Bone Spine. 2001;68(5):430-3.
5. Pasternak RC, Smith SC, Bairey-Merz CN, et al. ACC/AHA/NHLBI clinical advisory on use and safety of statins. J Am Coll Cardiol. 2002;40:567-72.
6. U.S. Food and Drug Administration. FDA launches a multi-pronged strategy to strengthen safeguards for children treated with antidepressant medications, United States 15 October 2004. Rockville, MD: Department of Health and Human Services, 2004; publication no. P04-97.
7. Overlack A. ACE inhibitor-induced cough and bronchospasm. Drug Saf. 1997;15(1):72-8.
8. “Anticholinergic.” Wikipedia.com. 2006. Wikipedia. 19 January 2007.
9. Friedman JD, Dello Buono FA. Opioid antagonist in the treatment of opioid-induced constipation and pruritus. The Annals of Pharmacotherapy. 2001;35(1):85-91.
10. Weintraub D, Siderowf AD, Potenza MN, et al. Association of dopamine agonist use with impulse control disorders in Parkinson’s disease. Arch Neurol. 2006;63:969-973.

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