The story may begin with one medication to treat high blood pressure, cholesterol, or a chronic disease, and after a while a new symptom appears, so it is treated as an independent health problem and another medication is prescribed, while it may originally be a side effect of the first medication.
Here begins what is known medically as the “prescription drug series” or “drug series,” when a side effect of one of the medications leads to prescribing a new treatment instead of discovering the true cause of the symptom.
This does not mean that every symptom that appears during treatment is caused by the medication, or that adding a new treatment is necessarily a wrong decision, but the emergence of a new health problem requires reviewing all the medications the patient is taking, and comparing the timing of starting treatment with the appearance of symptoms, before assuming the presence of a new disease.
How does the drug series start?
Dr. Muhammad Al-Asha, senior consultant in internal medicine at The View Hospital in Qatar, says that one of the important mistakes begins when the disease is evaluated in isolation from the patient’s complete health condition, instead of looking at him as a person who may suffer from more than one disease at the same time, or who carries risk factors for developing other diseases in the future.
Al-Asha explained in his interview with Al-Jazeera Net that, for example, a patient with high blood pressure should not be evaluated based on this disease alone, but attention should also be paid to the possibility of the presence of diabetes, fatty liver, sleep apnea, and other health problems that may occur in the same person.
He adds that this also applies when prescribing cholesterol-lowering medications, as the patient’s health condition and risk factors should be fully evaluated, especially if he is at risk of developing metabolic syndrome, which includes a group of problems such as high blood sugar, blood pressure, lipid abnormalities, and excess fat around the abdomen, which in turn raises the risk of heart disease and diabetes.
A scientific review published in 2026 in the journal Drugs & Aging defines drug cascade as a condition that occurs when a drug causes a side effect, and then this effect is treated with another drug instead of identifying its cause.
The review found that this phenomenon still does not receive sufficient attention, and that it may contribute to the inappropriate use of several medications, especially in older people.
When a side effect becomes a new disease
The series may begin with a seemingly simple offer. Some blood pressure medications, for example, can cause swelling in the feet, but this swelling may be interpreted as a new problem that requires the prescription of additional medication.
A study published in JAMA Internal Medicine, which included more than 41,000 elderly people with high blood pressure, showed that people who started taking calcium channel blockers were more likely to be prescribed a diuretic later.
The study indicated that swelling of the extremities resulting from these medications may be mistakenly interpreted as fluid retention that requires a diuretic, although this type of swelling does not usually result from an increase in fluids in the body, which makes reviewing the causative medication an important step before adding a new treatment.
Al-Asha points out that medications for chronic diseases have known side effects, and therefore the patient’s knowledge of what should be monitored after starting treatment helps him discover the problem early, instead of treating it as a separate disease.
He gives the example of some cholesterol-lowering medications that can be associated with high blood sugar or muscle pain, stressing the importance of choosing the appropriate treatment from the beginning, involving the patient in the treatment plan, and explaining the symptoms that he should pay attention to.
A 2024 meta-analytic review in The Lancet Diabetes & Endocrinology concluded that cholesterol-lowering statins were associated with a limited increase in blood sugar and the likelihood of being diagnosed with diabetes, and that most of the additional cases occurred in people whose blood sugar levels were already close to the limit used to diagnose the disease.
An analysis published in The Lancet also showed that statin use is associated with a limited increase in muscle pain or weakness, especially during the first year of treatment.
Who needs more attention?
A drug chain can happen to anyone, but its probability becomes more important as the number of medications and diseases that the patient suffers from increases, as distinguishing between the symptoms of the disease and the effects of treatment may become more difficult.
Al-Asha stresses the importance of follow-up after starting some treatments for chronic diseases, explaining that some medications used to treat blood pressure and heart disease may affect kidney function or raise the level of potassium in the blood, and therefore the patient needs follow-up tests at the time specified by the doctor.
For specific classes of heart and blood pressure medicines, NICE guidelines recommend checking kidney function and electrolytes before starting treatment, and then repeating the test, usually within one to two weeks of starting the drug and after increasing the dose.
Follow-up may preclude another medication
Al-Asha provides another example with modern medications used to treat diabetes, known as “sodium-glucose co-transporter type 2” (SGLT2) inhibitors, which help the body get rid of part of the glucose through the urine, and their benefits extend to groups of patients to protect the heart and kidneys.
He stresses the importance of educating the patient from the beginning about the necessity of taking fluids appropriately, paying attention to symptoms that may indicate the occurrence of an infection, and communicating with the doctor when they appear, so that the condition can be evaluated and the appropriate action can be determined instead of adding medication or stopping treatment randomly.
The 2026 American Diabetes Association standards recommend that users of these medications be aware of the possibility of fungal infections in the genital area and dehydration, while paying attention to the symptoms of urinary tract infections and dealing with them when they occur.
Also, contracting a minor infection does not automatically mean stopping the medication, as the decision depends on the nature and severity of the infection and the patient’s health condition.
Medicines we may not need
Al-Asha emphasizes that prevention of the drug chain begins with “treating the entire patient,” using doses that achieve the desired therapeutic goal, and not prescribing treatment without a clear medical need.
He points out that medical guidelines represent a road map that guides the doctor, but they work alongside his experience and knowledge of the patient’s health condition and his ability to involve him in the treatment decision, to reach the best possible result and avoid medications that he does not need.
Therefore, the appearance of a new symptom after starting one medication does not mean that the patient should stop treatment on his own, nor does it necessarily mean that he needs another medication.
The most important step is to review the timing of the symptom’s appearance, the list of medications and doses, and any recent changes that have occurred, then determine whether the problem is actually a new disease, or a side effect that can be dealt with by adjusting the dose, changing the medication, or by any other option that the doctor deems appropriate.
Reviewing the entire list of medications becomes more important when a new treatment is added, or symptoms that were not present before appear, or when the patient follows up his condition with more than one doctor.
Here the question that prevents the start of an unnecessary drug series may not be: “What medication treats this symptom?”, but rather: “Could it be one of my medications that caused it?”