Common chemotherapy adverse effects

01OverviewDefinition, clinical context and the essential points that orientate the chapter.

Cytotoxic adverse effects arise because normal marrow, mucosa, hair follicles, gonads and some organs share vulnerabilities with malignant cells. Timing helps interpretation: infusion reactions occur during administration, emesis may be acute or delayed, neutrophil nadir follows a regimen-specific pattern and cumulative neuropathy or cardiac injury worsens over cycles. Timing never overrides physiology, and a patient can become septic outside the expected nadir.

Assessment begins with ABCDE stability, exact regimen and cycle day, prophylaxis, comorbidity and concurrent medicines. Full blood count, renal, hepatic, electrolytes and infection tests are selected from the syndrome. Other causes remain active: diarrhoea may be infectious, abdominal pain may be obstruction or perforation, fatigue may be anaemia or endocrine disease, and breathlessness may be embolism or pneumonitis.

Management combines immediate rescue, symptom control and protection of future treatment. Hydration, antiemetics, mouth care, analgesia, transfusion or growth-factor pathways are used when indicated. The oncology team determines subsequent dose modification from severity, duration, response, intent and alternatives. A curative regimen and a low-benefit palliative regimen may justify different toxicity trade-offs.

Key points

Treatment toxicity is predicted by regimen, dose, cycle day, organ reserve and previous reaction; obtain the exact SACT record rather than relying on the drug class alone.
Myelosuppression causes infection, bleeding and symptomatic anaemia, but clinical deterioration is treated before a laboratory nadir is confirmed.
Nausea and vomiting need emetogenic-risk prophylaxis plus rescue treatment; refractory symptoms prompt assessment for obstruction, metabolic disturbance, brain disease and infection.
Mucositis and diarrhoea can cause dehydration, malnutrition, infection and dose interruption; severity is measured by intake, stool frequency, bleeding and physiology.
Peripheral neuropathy, fatigue, cognitive complaints, alopecia and fertility effects can be dose-limiting even when they are not immediately life-threatening.
Renal, hepatic, cardiac, pulmonary and bladder injury are agent-specific and should not be hidden under the label of common chemotherapy effects.
Supportive medicines have their own constipation, sedation, QT, glucose and interaction harms and require reconciliation.
Every significant adverse event needs documentation, causality review and a clear decision to continue, delay, reduce, substitute or stop the next cycle.

02AetiologyUnderlying causes, associations and risk factors, with why each one matters.

Direct normal-tissue injury

Cytotoxic medicines damage proliferating marrow, mucosal, hair and gonadal cells alongside cancer, producing predictable but regimen-dependent adverse effects.

Agent-specific organ exposure

Individual medicines accumulate in or injure heart, lung, kidney, liver, nerves or bladder through mechanisms beyond general cell division.

Host and treatment modifiers

Age, frailty, organ function, genetics, interactions, prior treatment and cumulative dose determine why toxicity differs between patients receiving the same regimen.

03PathophysiologyThe causal sequence from the underlying abnormality to symptoms and harm.

1
Marrow production falls
Suppressed progenitor cells reduce neutrophil, platelet and red-cell production, creating delayed infection, bleeding and anaemia risk.
2
Barrier tissues break down
Mucosal injury causes pain, diarrhoea and loss of protective integrity, promoting dehydration, malnutrition and microbial translocation.
3
Organ damage accumulates
Reactive metabolites, oxidative injury, microtubule disruption or immune effects impair susceptible organs, sometimes continuing after the medicine is stopped.
4
Recovery competes with retreatment
Normal tissues repair between cycles, but incomplete recovery and cumulative exposure can convert reversible symptoms into prolonged or permanent disability.

04Clinical features and red flagsSymptoms, examination findings, patterns of presentation and time-critical warnings.

Neutropenic sepsisRed flag

Recent chemotherapy with fever, rigors or unexplained deterioration requires immediate cultures and the first empirical intravenous antibiotic, targeted within 1 hour of acute presentation, without waiting for neutropenia to be confirmed.

Mucositis with poor intake

Oral ulceration, odynophagia or diarrhoea can rapidly cause dehydration, malnutrition, electrolyte loss and secondary infection.

Cumulative neuropathy

Distal numbness, pain, gait change or impaired fine motor function may worsen cycle by cycle and become irreversible.

Symptomatic anaemia or bleeding

Breathlessness, chest pain, syncope, bruising or mucosal bleeding requires blood count and clinical severity assessment.

Agent-specific organ injury

New chest, respiratory, renal, hepatic, urinary or neurological symptoms must be matched to the actual medicines and differentials.

05InvestigationsWhat to request, why it matters and how to interpret it.

Investigation order

Read from the initial assessment onwards. Tests may run in parallel in urgent care; first-line, preferred, confirmatory, definitive and gold-standard labels appear only when the chapter explicitly states them.

01
Full blood countFirst step
Why
Detect neutropenia, thrombocytopenia and anaemia after treatment.
Interpretation and limitations
Interpret with symptoms and expected trajectory; severe illness is treated immediately and unexpected multilineage change prompts broader review.
02
Renal, hepatic and electrolyte profile
Why
Measure dehydration, organ injury and medicine clearance.
Interpretation and limitations
Compare with pre-cycle baseline and replace deficits carefully; acute kidney or hepatic change can prolong cytotoxic exposure.
03
Cultures and lactate
Why
Assess infection and shock in a deteriorating patient.
Interpretation and limitations
Take cultures promptly, including central access where appropriate, but never delay empirical neutropenic-sepsis antibiotics.
04
Toxicity-focused examination
Why
Grade mucosal, bowel, skin, neurological and hydration effects from baseline.
Interpretation and limitations
Functional effect, intake, stool count and objective deficit matter; grades support but do not replace escalation judgement.
05
Agent-specific cardiac, lung or imaging test
Why
Investigate a suspected organ complication or important mimic.
Interpretation and limitations
Select ECG, troponin, echocardiography, chest CT or abdominal imaging from the syndrome rather than ordering a generic toxicity panel.

06Differential diagnosisRealistic alternatives and the features that help distinguish them.

Cancer progression

New pain, obstruction, neurological deficit or weight loss can reflect advancing disease rather than treatment and requires objective reassessment.

Infection

Fever, diarrhoea, cough and mucositis may be infectious with or without neutropenia, and immunosuppression can blunt typical inflammatory signs.

Supportive-medicine toxicity

Opioids, antiemetics, corticosteroids and antimicrobials can cause constipation, sedation, dysglycaemia, QT change or organ injury that mimics chemotherapy effects.

Unrelated acute illness

Thrombosis, cardiac disease, endocrine disorders and surgical emergencies remain possible during chemotherapy and should not be hidden by treatment attribution.

07ManagementImmediate care, first-line treatment, alternatives and escalation.

01TriageIdentify what cannot waitFirst stepA chemotherapy-treated patient contacts the service with new symptoms.

1Obtain regimen, cycle day, temperature and ABCDE red flags and direct fever or deterioration to immediate acute assessment.
2Use the 24-hour oncology line and do not rely on a normal home temperature after antipyretic use or early presentation.
3Treat sepsis, bleeding, dehydration, thrombosis and organ failure in parallel with confirming treatment causality.

02SupportTreat common reversible toxicityThe patient is stable but symptoms threaten hydration, nutrition, function or adherence.

1Optimise regimen-matched antiemesis, mouth care, analgesia, bowel treatment, hydration and nutritional support with interaction review.
2Correct electrolytes and anaemia or platelet problems through the appropriate protocol, investigating infection and blood loss where relevant.
3EscalationEscalate persistent or atypical symptoms to imaging or organ specialists rather than repeatedly adding symptomatic medicine.

03ModifyProtect the next cycleA clinically important adverse effect has occurred.

1Document onset, maximum severity, treatment, recovery and whether toxicity is expected, cumulative or idiosyncratic.
2Oncology reviews delay, dose reduction, prophylaxis, substitution or cessation against treatment intent and cancer response.
3Communicate the modified prescription and emergency plan across prescriber, pharmacy, administration unit and patient before further treatment.

Key medicines and prescribing safety2 treatments · regimens, roles and cautions

Initial beta-lactam monotherapy recommended by NICE when neutropenic sepsis is suspected, unless patient-specific or local microbiological factors require an alternative.

Piperacillin/tazobactam for suspected neutropenic sepsis

Administer 4.5 g intravenously as the first adult dose immediately; ongoing licensed febrile-neutropenia dosing is 4.5 g every 6 hours, adjusted for renal function and then for local resistance, allergy, cultures and clinical response.

Obtain cultures without delaying the antibiotic, verify serious beta-lactam allergy, resuscitate shock and seek source control. Monitor renal, hepatic and haematological toxicity and avoid routine extra aminoglycoside or glycopeptide without an indication.

Prevents acute and delayed chemotherapy-related nausea and vomiting as one component selected from the regimen's emetogenic-risk protocol.

Ondansetron (5-HT3 antiemetic example)

For moderately emetogenic chemotherapy, a licensed adult oral schedule is 8 mg 1–2 hours before treatment followed by 8 mg 12 hours later, then 8 mg twice daily for up to 5 days. Highly emetogenic regimens need protocol-defined combination prophylaxis; moderate or severe hepatic impairment limits the total daily dose to 8 mg.

Review QT prolongation, bradyarrhythmia, electrolyte disturbance, constipation or obstruction and serotonergic combinations. Persistent vomiting requires hydration and assessment for infection, metabolic disturbance, intracranial disease or bowel obstruction.

08ComplicationsImportant consequences, why they occur and why they matter clinically.

Neutropenic sepsis

Impaired innate immunity permits rapidly progressive infection and shock, sometimes with minimal localising signs or fever.

Bleeding and symptomatic anaemia

Thrombocytopenia and reduced red-cell production can cause haemorrhage, myocardial strain, breathlessness, functional decline and treatment delay.

Dehydration and malnutrition

Vomiting, diarrhoea and mucositis reduce intake and increase losses, causing kidney injury, electrolyte disturbance and functional decline.

Persistent organ disability

Cumulative neuropathy, cardiomyopathy, lung injury, infertility or renal damage can remain long after cancer treatment ends.

09Monitoring and follow-upTreatment response, safety checks and longer-term review.

During acute illness trend observations, lactate, urine output, blood count, renal, hepatic and electrolytes until physiology and marrow recover.
Record stool frequency, oral intake, weight, pain, mucosal grade and functional neuropathy rather than using a general unwell label.
Review supportive-medicine adherence and toxicity, especially constipation, sedation, glucose change and QT-prolonging combinations.
Before the next cycle confirm full recovery or the planned modification and ensure all treatment systems display the same decision.
After completion monitor persistent neuropathy, cardiac, pulmonary, renal, fertility and second-malignancy risks linked to cumulative exposure.

10Special situationsVariants, exceptions and circumstances that change the usual approach.

Common can be severe

Diarrhoea and mucositis are frequent, but volume loss, translocation and inability to take medicines can make them critical illnesses.

Timing guides not rules

Expected nadir informs risk, yet infection and organ toxicity can occur at any point after treatment.

Function grades toxicity

A symptom's effect on walking, eating, self-care and sleep may determine treatment modification before a dramatic laboratory change.

Supportive drugs interact

Antiemetics, opioids, laxatives and corticosteroids can create sedation, constipation, dysglycaemia and QT risk that resembles or worsens toxicity.

Intent changes tolerance

Dose preservation for cure is balanced differently from repeated severe toxicity during treatment with marginal disease-control benefit.

11Common pitfallsFrequent interpretation and management errors.

01
Waiting for a low neutrophil count before antibiotics.
02
Calling severe diarrhoea routine without infection assessment.
03
Ignoring cumulative functional neuropathy in clinical practice.
04
Treating vomiting without excluding obstruction.
05
Forgetting supportive-medicine adverse effects in clinical practice.
06
Repeating the same dose after severe toxicity.