Carboplatin Side Effects: What to Expect and When to Call Your Doctor

Carboplatin is one of the most widely used and well-tolerated platinum-based chemotherapy drugs, particularly when compared to its predecessor cisplatin. However, like all chemotherapy, it causes side effects that patients should understand before and during treatment. Knowing what is normal — and what is a warning sign requiring immediate attention — can help you stay safe and comfortable throughout your treatment.

The Most Important Side Effect: Bone Marrow Suppression (Myelosuppression)

Myelosuppression — the suppression of bone marrow blood cell production — is the primary dose-limiting side effect of carboplatin, and it carries a boxed warning. Carboplatin is more likely to cause thrombocytopenia (low platelets) than cisplatin, and this can lead to serious bleeding. It also causes neutropenia (low white blood cells) and anemia (low red blood cells).

The lowest point of blood counts (called the nadir) typically occurs 21–28 days after your first carboplatin infusion. Your oncologist will monitor your complete blood count (CBC) closely throughout treatment.

Low platelets (thrombocytopenia): Watch for unusual bruising, prolonged bleeding from cuts, blood in urine or stool, or heavy menstrual bleeding. Report any of these immediately.

Low white blood cells (neutropenia): Increases your infection risk. Call your doctor right away if you develop fever (temperature ≥100.4°F or 38°C), chills, painful urination, or skin sores.

Anemia: May be cumulative over treatment cycles and may require a blood transfusion. Symptoms include fatigue, shortness of breath, and pale skin.

Nausea and Vomiting

Nausea and vomiting are frequent carboplatin side effects, although carboplatin causes significantly less nausea than cisplatin. Your oncology team will typically pre-medicate you before your infusion with antiemetic medications — usually a 5-HT3 receptor antagonist (such as ondansetron) plus dexamethasone — to reduce these effects.

If nausea or vomiting is severe enough to prevent eating or drinking for more than 24 hours, contact your oncology team.

Anaphylactic and Hypersensitivity Reactions

Severe allergic reactions to carboplatin can occur within minutes of infusion and represent a medical emergency. This risk is part of the boxed warning for carboplatin. The risk increases with repeated exposure — particularly after 6–8 cycles. Symptoms of a hypersensitivity reaction include:

Hives or skin rash

Difficulty breathing or chest tightness

Swelling of the face, lips, or throat

Drop in blood pressure, dizziness, or loss of consciousness

Your infusion center should have epinephrine, corticosteroids, and antihistamines immediately available during carboplatin administration.

Other Common Side Effects

Fatigue and weakness: Very common; rest as needed and maintain light activity if possible.

Peripheral neuropathy: Numbness, tingling, or burning in hands and feet. Occurs in 4–15% of patients at conventional doses but is generally less severe than with cisplatin or oxaliplatin.

Electrolyte abnormalities: Low magnesium (hypomagnesemia) and low potassium (hypokalemia) can occur. Your team monitors electrolytes and may provide supplements.

Hair loss (alopecia): May occur, particularly when carboplatin is combined with taxanes like paclitaxel. Hair typically grows back after treatment ends.

Loss of appetite: Common during treatment. Work with your care team and a registered dietitian to maintain adequate nutrition.

When to Call Your Doctor Immediately

Call your oncology team right away or go to an emergency room if you experience any of the following after a carboplatin infusion:

Fever ≥100.4°F (38°C) — could signal serious infection in the context of neutropenia

Signs of allergic reaction: hives, difficulty breathing, swelling, sudden drop in blood pressure

Unusual or uncontrolled bleeding, black tarry stools, or blood in urine

Severe nausea/vomiting preventing eating or drinking for more than 24 hours

Sudden or severe worsening of numbness or tingling in hands or feet

It is also important to know about carboplatin's interactions with other medications. Read our guide on carboplatin drug interactions to ensure your full medication list is reviewed by your oncology team before treatment begins.