Side effect and toxic effect are two subclasses of adverse drug effects [1]. But often these terms ‘side effect’ and ‘toxic effect’ are used interchangeably. When a patient administers a drug, two types of effects occur therapeutically desired effects and undesired effects. Most importantly, all medicines can cause therapeutically unexpected side effects along with beneficial effects. Intensity and incidence of side effects and toxic effects are linked to the size of the dose [2].
Do you know Dose, Dosage, Dosage form? More differences between Side Effect and Toxic Effect are given in the below table.
Table of Contents
1. Definition side effect and toxic effect
The side effect is defined as the therapeutically undesired but often unavoidable effect that occurs at the normal therapeutic doses of a drug. Generally, side effects are not serious effect, they can be predicted from a drug pharmacological profile in a given dose of the drug. Simply, side effects are unwanted but often unavoidable pharmacodynamics effects that occur at therapeutic doses [1]. In short, the side effect is any undesired effects produced by a drug other than the desired therapeutic effect.
On the other hand, the toxic effect is a deleterious, undesired but often avoidable effect caused by the excessive pharmacological action of the drug at a normal dose for prolong use or overdose for the normal period. Probably, the toxic effects of drugs either related to major pharmacological actions such as bleeding with anticoagulants or unrelated to the main pharmacological action such as liver damage due to paracetamol overdose [3].
2. Side effects are unwanted but frequently unavoidable. For example, calcium carbonate is taken to treat calcium deficiency or osteoporosis, but constipation is unavoidable side effects here. While toxic effects can be avoided by careful and wise use of the drug.
3. Side effects are not often deleterious, they are therapeutically unexpected and but not life-threatening. On the other hand, toxic effects are deleterious and they are often life-threatening.
4. Occurrence of side effects and toxic effect
Side effect occurs within the normal therapeutic dose of a drug. On the other hand, the toxic effect occurs due to overdose or the repeated dose of a drug. Here, the therapeutic dose is the predetermined amount of drug which will produce the optimal therapeutic effects.
5. The side effect is expected (therapeutically unexpected) and reduction or discontinuation of drugs not necessary. While reduction or discontinuation of the drug is needed in case of toxic effect.
6. Often no need to treat side effects. But in some severe case side effects are treated to reduce discomfort or complications. In the case of toxic effects, treatment or antidote must require. For example, N-acetylcysteine must require in hepatotoxicity caused by paracetamol overdose.
7. Examples of side effect and toxic effect
List of examples of side effect
| Name of Drug | Indication | Common Side effects |
| Morphine | Analgesic | Constipation, vomiting. |
| Calcium carbonate | Calcium Deficiency | Constipation, dry mouth, stomach pain, vomiting. |
| Caffeine | Neonatal respiratory distress | Insomnia, Dizziness, tachycardia[4] |
| Isoniazid | Tuberculosis | Peripheral neuritis, Hepatotoxicity[4] |
| Phenelzine | Depression | Insomnia, CNS excitation, orthostatic, hypotension[4] |
| Clonazepam | Epilepsy | Ataxia, slurred speech, dizziness[4] |
| Sulfonamides | Antibacterial agents | Hypersensitivity, Fever, Hemolytic anemia, Lupus-like syndromes[4] |
List of examples of toxic effect
| Name of Drug | Indication | Toxic effects |
| Paracetamol | Analgesic and Antipyretic | Hepatotoxicity with overdose. |
| Morphine | Analgesic | Respiratory failure with the overdose |
| Streptomycin | Antitubercular | Vestibular damage on prolonged use |
| Imipramine | antidepressant | Cardiac arrhythmia with overdose |
| Chloramphenicol | Antibiotic | Aplastic Anemia with the overdose |
Summary of the difference between side effect and toxic effect
| Side Effect | Toxic Effect | |
| 1. | The side effect is defined as the therapeutically undesired but often unavoidable effects that occur at the normal therapeutic doses of a drug. | The toxic effect is a deleterious, undesired but often avoidable effect caused by the excessive pharmacological action of the drug at a normal dose for prolong use or overdose for the normal period. |
| 2. | Unwanted but frequently unavoidable. | Avoidable by the careful and wise use of drug. |
| 3. | Non-deleterious effect [4] | Deleterious effect[4] |
| 4. | It is a normal pharmacological effect of a drug. | It is a noxious pharmacological effect of a drug |
| 5. | Occurs within the normal therapeutic dose. | Occurs due to overdose or repeated dose. |
| 6. | Reduction or discontinuation of drugs not necessary. | Reduction or discontinuation of the drug is needed. |
| 7. | Mild and self-resolving and often not required any treatment. | Severe and requires treatment. |
| 8. | Less dangerous for the patient and generally not life-threatening. | More harmful for patients and life-threatening. |
| 9. | Often expected with therapy. | Unexpected with therapy. |
| 10. | Do not deter the main pharmacological effect of the drug. | Deter the main pharmacological effect of the drug and lead to more complications. |
| 11. | Examples of side effects: Constipation, vomiting by Morphine (Analgesic). Constipation, dry mouth, stomach pain, vomiting are common side effects during osteoporosis treatment by Calcium carbonate [5]. | Examples of toxic effects: Hepatotoxicity with Paracetamol overdose, Aplastic Anemia by Chloramphenicol. |
Also read:
- First, Difference between pharmacokinetics and pharmacodynamics
- Second, Difference between poison and toxin
- Third, Difference between drug abuse and misuse
- Fourth, Difference between Signs and Symptoms
However, side effects and toxic effects both are unexpected by scientists, doctors, pharmacists as well as patients. Scientists always try to minimize side effects and toxic effects of a drug. Stay connected and leave a comment about the difference side effect and toxic effect.
References
- Tripathi, K. D. (2019). Essentials of medical pharmacology.
- American Society of Health-System Pharmacists. ASHP guidelines on adverse drug reaction monitoring and reporting. Am J Health-Syst Pharm. 1995;52(4):417-419.
- Ritter, J., Flower, R. J., Henderson, G., MacEwan, D. J., Loke, Y. K., & Rang, H. P. (2020). Rang and Dale’s pharmacology.
- Goodman, Louis Sanford, Alfred Gilman, Laurence L. Brunton, John S. Lazo, and Keith L. Parker. 1990. Goodman & Gilman’s the pharmacological basis of therapeutics. New York: McGraw-Hill Companies
- “Calcium Carbonate”. MedlinePlus, American Society of Health-System Pharmacists, 09/15/2015. https://medlineplus.gov/druginfo/meds/a601032.html ;Retrieved 20 February 2020.