Chemotherapy Side Effects and Nutrition

Chemotherapy and other systemic anticancer treatments frequently produce side effects that directly impair the ability to eat, digest, and absorb food: nausea and vomiting, altered taste and smell, mucosal injury, diarrhoea or constipation, and reduced appetite. This topic concerns how those treatment toxicities undermine nutritional status and why nutritional assessment is part of supportive cancer care.

Definition

Chemotherapy-related nutritional toxicity refers to the cluster of treatment side effects (such as nausea, vomiting, mucositis, dysgeusia, diarrhoea, and anorexia) that reduce dietary intake, impair digestion or absorption, and thereby threaten nutritional status during systemic anticancer therapy.

Scope

The topic surveys the principal gastrointestinal and intake-related toxicities of systemic anticancer therapy and their nutritional consequences, the rationale for monitoring nutritional status through treatment, and the role of supportive nutrition. It is a reference overview and does not provide antiemetic regimens, supplement prescriptions, or individualized dietary plans.

Core questions

• Which chemotherapy side effects most directly threaten nutritional intake and status?
• Why does treatment-related toxicity warrant ongoing nutritional monitoring?
• How does nutritional support fit alongside symptom control during anticancer therapy?

Key concepts

• Chemotherapy-induced nausea and vomiting
• Dysgeusia and taste alteration
• Treatment-related diarrhoea and malabsorption
• Anorexia during treatment
• Nutritional screening through the treatment course

Mechanisms

Cytotoxic and many targeted agents act on rapidly dividing cells, including the epithelial lining of the gastrointestinal tract, and on central pathways that regulate nausea and appetite. The result is a set of intake-limiting effects: emetogenic stimulation producing nausea and vomiting, mucosal injury producing mouth and gut soreness, altered taste and smell reducing food appeal, and accelerated or disrupted transit producing diarrhoea or constipation. These effects compound the anorexia and metabolic changes of the underlying cancer, so that even short treatment cycles can produce meaningful intake deficits if not anticipated.

Clinical relevance

Because treatment toxicity can rapidly reduce intake, nutritional screening and support are integrated into oncology pathways so that deficits are recognized early and patients can complete planned therapy. This entry describes the nutritional dimension of treatment side effects for reference; symptom management and any nutritional intervention are individualized and directed by the treating team.

Epidemiology

Gastrointestinal and intake-related side effects are among the most commonly reported toxicities of systemic anticancer therapy, with frequency and severity depending on the agents, doses, and regimen used. As the number of people receiving and surviving cancer treatment grows, the population affected by treatment-related nutritional toxicity is correspondingly large.

Evidence & guidelines

ESPEN guidance on nutrition in cancer patients (Arends et al., 2017) and the ESPEN practical guideline (Muscaritoli et al., 2021) address nutritional screening and support during anticancer treatment, including management of intake-limiting toxicities, while the ESPEN expert group recommendations (Arends et al., 2017) call for systematic action against cancer-related malnutrition.

Key figures

• Jann Arends
• Maurizio Muscaritoli
• Federico Bozzetti

Seminal works

• arends-2017-espen
• muscaritoli-2021-espen

Frequently asked questions

Are nutritional side effects the same for every chemotherapy regimen?

No. The type and severity of intake-limiting toxicities depend heavily on the specific agents and doses; some regimens are strongly emetogenic or mucotoxic while others are not, which is why nutritional monitoring is tailored to the treatment.

Does losing weight during chemotherapy always mean cachexia?

Not necessarily. Weight loss during treatment may reflect reduced intake from controllable side effects, the metabolic cachexia of the cancer itself, or both; distinguishing them helps direct the right combination of symptom control and nutritional support.