Side effect

What Is a Treatment-Related Side Effect?

A side effect is defined as a problem that occurs when a treatment goes beyond the desired effect. A side effect can also be a problem that occurs aside from the normal therapeutic effect. Side effects occur due to the use of certain medications, physical problems and illnesses, and from various mental disorders.

A side effect can be considered as an unexpected medical problem that occurs during treatment with medication or other type of therapy. Side effects can range from mild to severe, and in some instances, can be life-threatening.


There are several factors that can cause a person to experience a side effect from a pharmaceutical drug, including both prescription medication and over-the-counter drugs. People can also experience side effects from various physical and mental illnesses. Common causes of side effects include:

  • A person’s reaction to ingredients present in the medication
  • Dosage
  • Interactions with other medications, vitamins, or substances such as alcohol
  • Withdrawal from alcohol, drugs, or prescription medication
  • Various mental disorders such as depression, anxiety disorder, schizophrenia, and more
  • Physical illnesses such as cancer, diabetes, heart disease, and others
  • Neurological diseases such as Alzheimer’s or Parkinson’s disease


There are several different types of side effects, which can range from mild to severe or life-threatening.

Common mild to moderate side effects include:

  • Drowsiness
  • Dizziness
  • Constipation
  • Nausea
  • Vomiting
  • Diarrhoea
  • Abdominal pain
  • Skin rash
  • Dry mouth
  • Headache
  • Muscle and joint pain or stiffness
  • Difficulty concentrating
  • Reduced sex drive
  • Loss of appetite

Some examples of more serious side effects can include:

  • Increased blood pressure
  • Respiratory problems
  • Internal bleeding
  • Cancer
  • Suicidal thoughts
  • Swelling of the face, lips, mouth, or tongue
  • Heart palpitations
  • Numbness
  • Hallucinations
  • Delusion
  • Hair loss
  • Haemorrhage
  • Nerve damage

Side Effects FAQ

Do side effects go away?

Most side effects will go away after a person has become accustomed to the medication in their body. If side effects do not go away, a person should speak with their doctor and discuss lowering the dosage or discontinuing the prescribed medication.

What is meant by common side effects?

Common side effects are those that are experienced by a significant number of people who take a medication or experience a certain condition. For example, a common side effect of chemotherapy is nausea, which affects several individuals who receive chemotherapy treatment for cancer.

What is the difference between a side effect and an adverse effect?

A side effect is something that is commonly experienced from a medication or condition, while an adverse effect is an undesired or harmful effect that is not expected.

Do all drugs cause side effects?

All drugs have the potential to cause side effects in an individual, but not everyone will experience the same (or any) side effects. Possible factors that can determine if a person will experience a side effect include how large the dosage, age, weight, whether a person is male or female, and any other co-occurring health problems.

External Links

Definition of Side effects, MedicineNet

What are side effects?, NHS

Side effects: Causes and types, Christian Nordqvist, Medical News Today

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