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Managing Common Drug Side Effects

Written by C. Fookes, BPharm on Nov 16, 2018


Every drug has side effects. How vulnerable you are to these side effects depends on many different factors, which can be generally grouped as patient-related, drug-related, and environmentally or socially-related. Find out if you have any characteristics that will increase your susceptibility to drug-related reactions, and what you can do to manage some of these possible side effects.

Risk of Developing Side Effects

Every one of us is unique. However, certain individual factors make some of us more likely to develop side effects than others.

The most significant of these factors is age. The very young and the very old are ALWAYS more susceptible to unwanted reactions.

Children are not small adults. The way their bodies absorb metabolize and eliminate drugs differs from adults, and this is especially true in babies. Younger children tend to absorb medicine more slowly from the stomach but have faster intramuscular (IM) absorption rates. In early life, they have a higher body water to lipid ratio and a larger liver to body weight ratio. Liver enzymes are immature as is their kidney function. In addition, the permeability of the blood-brain barrier (the layer of cells that restricts the passage of substances from the bloodstream to the brain) is higher.

Older adults typically take more medicines and studies have shown they are twice as likely to go to ED because of an adverse drug event and seven times more likely to be hospitalized. They are more likely to be on medicines with a narrow margin between being effective or toxic such as warfarin, insulin, digoxin, and anti-seizure medications. Their bodies tend to have more fat and less water which may increase the duration of effect of certain drugs. In addition, metabolism in the liver and excretion through the kidneys is typically reduced. Their brains are also more sensitive to the sedating effects of a drug, and pre-existing problems, such as dizziness, eye, and ear problems, may be exacerbated increasing the risk of falls.

Individual Factors That Also Increase Risk

Several other factors also play a significant role in your likelihood of side effects. Some notable examples include:

  • Genetics: Pharmacogenetics is the name given to the study of how your genes influence your reaction to drugs and genetic factors account for 20-95% of patient variability. This field of pharmacology is rapidly evolving and testing for liver enzyme variations becoming more widespread. For example, codeine requires metabolism through CYP2D6 for conversion to one of its active metabolites, morphine. 5-10% of patients are poor metabolizers - which means that very little codeine is converted to morphine which results in insufficient pain relief. However, 1-2% of people are ultra-rapid metabolizers and more codeine is converted into morphine than normal, resulting in a higher risk of toxic reactions including respiratory depression
  • Kidney function If your kidneys are not functioning at full capacity, then side effects are more likely if you are taking drugs that are excreted through the kidneys. Some other drugs also cease to be effective when kidney function is reduced.
  • Gender: Females have a lower activity of certain hepatic enzymes, a higher body fat to water ratio, and a decreased clearance of drugs through the kidneys than men. Studies have shown the incidence of drug-induced liver toxicity, gastrointestinal side effects, allergic skin reactions, and long QT syndrome is higher in females.

Drug-Related Factors

Drug-related influences include:

  • The dose of the drug: The higher the dosage the greater the risk of side effects
  • The formulation being used: For example, inhaled steroids directly target the lungs and produce fewer side effects than oral steroids that have more of a body-wide effect
  • How the drug is absorbed, metabolized, distributed and eliminated
  • Other administered drugs.

Environmentally or Socially Related Influences

Environmentally or socially-related influences include:

  • Level of alcohol intake: Alcohol can intensify some side effects such as drowsiness, confusion, changes in blood pressure, abnormal behavior, respiratory depression, and nausea and vomiting
  • Smoking: The hepatic enzymes CYP 1A2 and 2B6 are induced by cigarette smoking. These enzymes metabolize several clinically important drugs (such as clozapine, olanzapine, and methadone), which means an abrupt cessation of smoking can increase blood levels of these drugs. Nicotine replacement therapy does not influence enzyme activity
  • Diet: Several medicines interact with foods. For example; atorvastatin with grapefruit, green leafy vegetables and warfarin, natural black licorice and lithium, salt and potassium supplements and ACE inhibitors, and tyramine-containing foods and MAOI antidepressants
  • Level of hydration: Dehydration can increase the risk of side effects of some medicines. Some medicines that shouldn't be taken by a person who is dehydrated include ACE inhibitors, NSAIDs, metformin and diuretics
  • Level of understanding about a medicine: Side effects are more likely if instructions are not clear, or a person is confused as to why they are taking a medicine; both of which may result in a wrong dosage being taken.

List of Common Drug Side Effects

The following table lists some of the more commonly encountered drug-related side effects and suggestions for their management.

Allergic Reactions

  • Potentially could occur with any medication.
  • Symptoms range from a mild rash to a severe anaphylactic reaction (including facial and throat swelling, difficulty breathing and a widespread rash).

Prevention and management strategies:

  • Take an antihistamine and see a doctor straight away if you think you are having an allergic reaction to a medicine. Seek emergency help if the reaction is severe
  • If the allergic reaction is confirmed as occurring due to that drug, avoid it and other related drugs in the future
  • Wear a medical alert tag to alert others to the medicine you are allergic too.

Blurred Vision

  • May occur with antihistamines, antipsychotics, bupivacaine, bupropion, duloxetine, esomeprazole, etodolac, gabapentin, opioids, and several other drugs.

Prevention and management strategies:

  • Talk to your doctor about switching medications
  • Lubricant eye drops may help
  • Avoid driving with impaired vision.

Bruising and Bleeding

  • Common with medicines that “thin the blood” such as aspirin, clopidogrel, enoxaparin, and warfarin. Also, common with NSAIDs, steroids (such as prednisone) and medicines to treat cancer.

Prevention and management strategies:

  • Try to avoid bumping yourself into furniture. Remove any trip hazards, such as loose rugs
  • Cuts may take longer to stop bleeding. Hold a gauze over the affected area and apply pressure
  • Seek emergency help if you have a wound that bleeds profusely or doesn’t stop bleeding within 15 minutes.


  • Common with opioids, diuretics, calcium antagonists, antidepressants, aluminum-containing antacids, ondansetron, and iron supplements.

Prevention and management strategies:

  • Increase water intake and fiber content of your diet (if appropriate)
  • Exercise, if possible
  • If mild, talk to your doctor about taking laxatives such as docusate, sennosides, or psyllium
  • If severe and caused by opioids, talk to your doctor about methylnaltrexone or naloxegol.


  • Common with ACE inhibitors (these can cause a dry, hacking, chronic cough in up to 20 percent of patients).

Prevention and management strategies:

  • Talk to your doctor about switching medications
  • Usually resolves one-to-two weeks after discontinuation.


  • Common with antihistamines, blood pressure medications, chemotherapy, and laxatives.

Prevention and management strategies:

  • Drink fluids. Cooled or iced fluids may go down easier
  • Eat moist foods such as fruits, vegetables, and soups
  • Regularly moisturize skin and apply lip balm
  • Apply lubricant to lips to avoid painful cracking.


  • May occur with some antibiotics, antidepressants, magnesium-containing antacids, proton pump inhibitors (eg, lansoprazole, omeprazole) and chemotherapy agents.

Prevention and management strategies:

  • If due to antibiotic use, talk to your doctor about taking probiotics
  • Talk to your doctor about antidiarrheal medication
  • Ask doctor about reducing the dosage of your drug or other suitable treatments
  • Keep up your fluid and electrolyte intake to avoid dehydration
  • If extremely persistent or severe, always tell your doctor.

Drowsiness or Sedation

  • Medications that cause drowsiness include benzodiazepines (such as lorazepam, diazepam), some antidepressants, antiemetics, older antihistamines (such as diphenhydramine, chlorpheniramine), some heart medications, muscle relaxants and narcotics.

Prevention and management strategies:

  • If your medication is making you drowsy during the day, talk to your doctor about reducing the dosage of your drug or other suitable treatments
  • Do not drive, operate machinery, or perform other hazardous tasks if affected
  • Avoid alcohol.

Dry mouth (Xerostomia)

  • May occur with antiarrhythmics, anticholinergics, antihistamines, drugs for high cholesterol, anti-inflammatory agents, diuretics, vasodilators, drugs for Parkinson’s Disease, and antipsychotics.

Prevention and management strategies:

  • Ask doctor about reducing drug dosage or other suitable treatments
  • Go for regular dental check-ups and ask dentist about application of sealants to teeth fissures
  • Eat low-sugar, low-acid foods
  • Avoid alcohol-containing mouthwashes
  • Chew xylitol chewing gum
  • Drug-treatments are available for people with Sjogren’s syndrome or a history of radiation therapy.

Erectile Dysfunction or Decreased Sexual Desire

  • More common with antidepressants, antihistamines, benzodiazepines, beta blockers, diuretics, and H2 blockers.

Prevention and management strategies:

  • Talk to your doctor about the possibility of switching to a different medication
  • Limit use of alcohol, smoking or recreational drugs such as marijuana which can also affect sexual function
  • Talk to your doctor about medications and other treatments for sexual dysfunction, such as prescription medications (for example PDE5 inhibitors), vacuum pumps, implants, surgery, and natural options.

Esophageal Damage

  • May occur with a wide-range of drugs including aspirin, bisphosphonates (such as alendronate), doxycycline, potassium chloride, quinidine, and vitamin C.

Prevention and management strategies:

  • Take all medicines while upright and swallow with a glass of water
  • Avoid lying down soon after taking a medicine
  • For some medicines, recommended advice includes remaining upright for 30 minutes after taking
  • Avoid irritating foods such as citrus and alcohol
  • Talk to your doctor about the possibility of switching to a different medication.

Indigestion or Gastroesophageal Reflux Disease (GERD)

  • May occur with drugs that irritate the stomach lining (such as aspirin, iron, NSAIDs, steroids), those that relax the lower esophageal sphincter (LES) (such as anticholinergics, calcium channel blockers, and nitrates) or reduce LES pressure (such as progesterone, theophylline, and tricyclic antidepressants).

Prevention and management strategies:

  • Talk to your doctor about reducing the dosage of, or switching to another drug
  • Elevate the head of the bed
  • Avoid foods that also irritate the stomach or affect the LES such as alcohol, carbonated beverages, citrus, coffee, fatty foods, or tomatoes
  • Quit smoking if you smoke, lose weight if you are overweight, avoid tight waistbands
  • Talk to your doctor about GERD medications such as antacids, H2 blockers and proton pump inhibitors.

Falling or Unsteadiness on Feet

  • Medicines that cause confusion, fatigue or sedation such as antipsychotics, some antidepressants, benzodiazepines, sedating antihistamines, antiepileptics, narcotics, and some heart medications.

Prevention and management strategies:

  • If sedation is the problem, talk with your doctor about changing the dose or trying an alternative medication
  • Remove rugs from the floor and throw rugs from furniture
  • Ask for help when getting up or walking
  • If you fall, tell your doctor and get checked for injuries
  • A home health nurse may be able to suggest ways to make your home safer
  • If you have a walker or wheelchair, use it every time you get up.

Gingival Enlargement (Growth of the gums around the teeth)

  • May occur with cyclosporine, calcium channel blockers (eg, nifedipine), and phenytoin.

Prevention and management strategies:

  • Requires dosage reduction or drug discontinuation
  • Surgical removal of gingival tissue is only temporarily effective if drug can’t be discontinued.


  • May occur with aspirin (low dose), chemotherapy agents, cyclosporine, frusemide, and thiazide diuretics.

Prevention and management strategies:

  • Talk to your doctor about reducing the dosage of, or switching to another drug
  • Your doctor may prescribe NSAIDs or other drugs to relieve the pain from gout
  • Avoid alcohol and purine-rich foods (cheeses, red meats) during the gout flare-up.


  • Common with asthma medications, angina and blood pressure medications, oral contraceptives, erectile dysfunction treatments, and stimulants
  • Rebound headaches can be caused by overuse of acetaminophen, aspirin, NSAIDs, and opioids.

Prevention and management strategies:

  • Talk to your doctor about alternative medications or a dosage reduction if the headaches are very debilitating
  • Some may respond to acetaminophen – but check with your doctor first
  • Rest in a quiet, dimly lit room
  • Heat, massage therapy, acupressure, or reflexology may help if the headaches recur
  • Keep well hydrated (drink plenty of water).


  • Corticosteroids, immunosuppressants, chemotherapy and several other medicines suppress your immune system and increase your risk of developing an infection.

Prevention and management strategies:

  • Wash your hands before eating, after contact with other people or animals, and after toileting
  • Stay away from people who are sick if your infection risk is increased (either by the medicines you are taking or the condition you have)
  • Keep up to date with your vaccinations (includes a yearly flu shot)
  • See your doctor as soon as you can if you develop symptoms of an illness and your immune system is compromised.

Hair Loss

  • May affect all body hair or just scalp hair
  • Common with chemotherapy or radiation therapy
  • May also occur with certain acne treatments, antibiotics, antidepressants, oral contraceptives, and cholesterol-lowering medicines.

Prevention and management strategies:

  • Be gentle when brushing or combing your hair. Avoid over-styling your hair. Wear a hair net to bed
  • Consider purchasing a wig while you still have hair to allow better matching with your original hair color. Wigs may be partly covered by insurance when called a “cranial prosthesis”
  • If due to chemotherapy or radiation therapy, ask your doctor about cooling caps.

Muscle Pain or Muscle Weakness

  • Common with statins (used to reduce cholesterol levels). May be due to an effect on muscle proteins or a decrease in coenzyme Q10 (CoQ10).

Prevention and management strategies:

  • Tell your doctor straight away because sometimes the muscle pain may indicate more severe damage. A lower dosage or a different medication may be needed
  • Avoid exercising too much
  • Do not take over-the-counter pain relievers such as acetaminophen or NSAIDs
  • Consider CoQ10 supplements; however, study results have been conflicting.

Nausea and Vomiting

  • Common with chemotherapy or radiation therapy
  • May also occur with drugs that tend to slow or block the bowel, when electrolytes are imbalanced or with infections.

Prevention and management strategies:

  • Antinausea medications (also called antiemetics) such as ondansetron, aprepitant, dexamethasone, and dronabinol can prevent vomiting and help control nausea. You may have to try several before finding one that works for you
  • Self-hypnosis, muscle relaxation, biofeedback, guided imagery and other “mindfulness” techniques may help
  • Acupuncture may help with anticipatory nausea
  • Eat small, frequent meals rather than large meals three times a day
  • Drink clear liquids cold and sip slowly. Try Popsicles or gelatine
  • Eat bland foods, such as dry toast and crackers and avoid fatty, fried, spicy, strong-smelling or very sweet foods
  • Try chewing ginger.

Taste Disturbances

  • Common with many drugs including antibiotics (such as ciprofloxacin, metronidazole), anticonvulsants, antidepressants, aspirin, blood pressure medications, lithium, metformin, and muscle relaxants.

Prevention and management strategies:

  • Usually reversible with drug discontinuation (although may take several months)
  • Prepare foods with a variety of colors and textures
  • Use herbs and spices (but avoid adding extra sugar or salt).

Tendonitis (tendinitis) or Tendon Rupture

  • Most commonly reported with fluoroquinolone antibiotics (eg, ciprofloxacin norfloxacin, ofloxacin, levofloxacin)
  • More common in people over the age of 60, taking corticosteroids, or with a history of organ transplant.

Prevention and management strategies:

  • Tell your doctor BEFORE you start taking the fluoroquinolone if you have had a tendon problem in the past
  • Avoid strenuous activity while taking the fluoroquinolone
  • Discontinue the antibiotic immediately if you experience pain or swelling in a tendon and seek medical advice
  • Avoid all fluoroquinolones in the future if you develop a tendon problem while taking a fluoroquinolone.

Weight Gain

  • Common with antipsychotics, most antidiabetic drugs (except for metformin), antidepressants and antiepileptics.

Prevention and management strategies:

  • Talk to your doctor about the possibility of switching to a different medication
  • Eat a healthy diet and limit your portion sizes
  • Eat more slowly at meals
  • Drink water throughout the day
  • Exercise regularly.

See Also


  1. Stephenson T. How children’s responses to drugs differ from adults. British Journal of Clinical Pharmacology. 2005;59(6):670-673. doi:10.1111/j.1365-2125.2005.02445.x.
  2. Adults and Older Adult Adverse Drug Events. Centers for Disease Control and Prevention. Medication Safety Program.
  3. Risk of Drug Side Effects Rises as You Age. Consumer Reports.
  4. Anderson, GD. Chapter 1. Gender Differences in Pharmacological Response. International Review of Neurobiology. Volume 83, 2008, Pages 1-10
  5. Dean L. Codeine Therapy and CYP2D6 Genotype. 2012 Sep 20 [Updated 2017 Mar 16]. In: Pratt V, McLeod H, Dean L, et al., editors. Medical Genetics Summaries [Internet]. Bethesda (MD): National
  6. Center for Biotechnology Information (US); 2012-. Available from:
  7. Alomar MJ. Factors affecting the development of adverse drug reactions. Saudi Pharmaceutical Journal 2014;22(2):83-94
  8. Lucas C. Martin J. Smoking and drug interactions. Aust Prescr 2013;36:102-43 DOI: 10.18773/austprescr.2013.037
  9. Hair Loss. American Cancer Society.
  10. How to overcome drug-induced constipation. April 4, 2016. The People’s Pharmacy.
  11. Taste Disorders. National Institute on Deafness and other Communication Disorders. May 2017. US Department of Health and Human Services.
  12. Bartok V. Drug-Induced Dry Mouth. Nov 2011.
  13. Gastroesophageal Reflux Disease (GERD, Heartburn).
  14. Drug-induced diarrhea. Medline Plus. US National Library of Medicine.

Further information

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.