What You Should Know About Amphotericin B Side Effects

Amphotericin B is one of the most powerful antifungal medications available — but it comes with a reputation. Doctors sometimes call it "Amphoterrible" because of its side effect profile, particularly with the conventional deoxycholate formulation. Understanding what to expect can help you feel more prepared and know when something needs immediate medical attention.

This guide covers the common and serious side effects of Amphotericin B, which populations need extra caution, and practical tips for managing symptoms during treatment.

What Is Amphotericin B? (Brief Overview)

Amphotericin B is a polyene antifungal medication used to treat serious, life-threatening fungal infections including invasive aspergillosis, cryptococcal meningitis, mucormycosis, systemic candidiasis, and others. It's administered intravenously in a hospital or infusion center. For a complete overview, see our guide on what Amphotericin B is, its uses, and dosage.

There are several formulations available, and the side effect profile differs between them:

• Conventional Amphotericin B Deoxycholate (Fungizone) — Most side effects, lowest cost
• Liposomal Amphotericin B (AmBisome) — Fewer side effects, especially kidney toxicity
• Lipid Complex Amphotericin B (Abelcet) — Intermediate side effect profile

Common Side Effects

Most patients receiving Amphotericin B will experience some of these side effects, especially during the first few infusions. They are generally manageable with premedication and supportive care:

• Fever and chills — The most classic side effect. Often called "shake and bake" by medical staff. Usually starts 1–3 hours into the infusion and can last several hours.
• Nausea and vomiting — Common during and shortly after infusion.
• Headache — Frequently reported, usually mild to moderate.
• Muscle and joint pain — Generalized body aches during or after infusion.
• Loss of appetite — Can persist throughout the treatment course.
• Diarrhea — Occurs in some patients.
• Injection site pain and swelling — Irritation at the IV site is common, especially with the conventional formulation.
• Flushing — Facial flushing during infusion.
• Weight loss — Can occur with prolonged treatment courses due to appetite loss and nausea.

These side effects tend to be worse with conventional Amphotericin B Deoxycholate and milder with the liposomal (AmBisome) formulation. Your medical team will typically premedicate you with acetaminophen, diphenhydramine (Benadryl), and sometimes hydrocortisone to reduce these reactions.

Serious Side Effects — When to Call Your Doctor

Amphotericin B can cause serious, potentially dangerous side effects that require immediate medical attention. These are less common but critical to watch for:

• Nephrotoxicity (kidney damage) — This is the most significant risk. Amphotericin B can damage the kidneys, leading to elevated creatinine, decreased urine output, and in severe cases, kidney failure. Your medical team will monitor your kidney function with regular blood tests. Symptoms to watch: significantly decreased urination, swelling in legs or ankles, persistent fatigue.
• Hypokalemia (low potassium) — Amphotericin B causes the kidneys to waste potassium, sometimes to dangerously low levels. This can cause muscle weakness, cramps, heart palpitations, and in severe cases, cardiac arrhythmias. Your team will check potassium levels regularly and supplement as needed.
• Hypomagnesemia (low magnesium) — Similar to potassium wasting, magnesium levels can drop and require supplementation.
• Anemia and blood disorders — Amphotericin B can suppress red blood cell production, leading to anemia. You may feel more tired and short of breath than usual.
• Hepatotoxicity (liver damage) — Jaundice (yellowing of skin or eyes), dark urine, or severe abdominal pain may indicate liver problems.
• Cardiac arrhythmias — Related to electrolyte imbalances (especially low potassium). Report any irregular heartbeat, chest pain, or palpitations immediately.
• Seizures — Rare but possible, especially with electrolyte disturbances.
• Anaphylaxis — Severe allergic reactions are rare but can occur. Symptoms include difficulty breathing, severe hives, swelling of the face or throat, and rapid drop in blood pressure.
• Pulmonary toxicity — Fluid buildup in the lungs can cause shortness of breath and coughing.
• Hearing loss or tinnitus — Ringing in the ears or decreased hearing should be reported.

Important: Amphotericin B carries an FDA boxed warning stating it should only be used for progressive and potentially life-threatening fungal infections. Overdose can be fatal.

Special Populations: Who Needs Extra Caution

• Pregnant patients — Amphotericin B is Pregnancy Category B, meaning animal studies haven't shown harm, but it should only be used during pregnancy when clearly needed. Discuss risks and benefits with your doctor.
• Breastfeeding patients — Amphotericin B is generally not recommended during breastfeeding. Talk to your doctor about the safest approach.
• Patients with existing kidney disease — Since Amphotericin B is nephrotoxic, patients with pre-existing kidney problems are at higher risk. The liposomal formulation (AmBisome) is often preferred for these patients as it's less kidney-toxic.
• Patients with heart disease or diabetes — Electrolyte shifts from Amphotericin B can be especially dangerous. Closer monitoring is required.
• Children — Pediatric patients may metabolize Amphotericin B faster than adults. Dosing adjustments may be needed.
• Patients receiving other kidney-toxic medications — If you're also taking medications that can harm the kidneys (aminoglycosides, cyclosporine, cisplatin), the combined risk is significant.

How to Manage Side Effects

Your healthcare team will take several steps to minimize side effects, but here's what you should know:

Before Each Infusion

• Premedication — Acetaminophen (Tylenol), diphenhydramine (Benadryl), and sometimes hydrocortisone are given 30–60 minutes before the infusion to prevent fever, chills, and nausea.
• IV hydration — A liter of normal saline is often infused before Amphotericin B to protect the kidneys. This is one of the most important protective measures.

During Treatment

• Slow infusion rate — Infusions typically run over 2–6 hours. Faster infusion rates increase side effects.
• Electrolyte monitoring — Potassium and magnesium levels are checked frequently, often daily. Supplements are given as needed.
• Kidney function tests — Creatinine and BUN levels are monitored regularly, sometimes daily during the first week of therapy.

At Home (Between Infusions)

• Stay well-hydrated — drink plenty of water and electrolyte-containing beverages.
• Take prescribed potassium and magnesium supplements as directed.
• Report new symptoms promptly — don't wait until your next infusion to mention something that doesn't feel right.
• Keep track of your urine output — significantly decreased urination is a warning sign.

Final Thoughts

Amphotericin B's side effects are real and sometimes uncomfortable, but they're manageable with proper medical supervision and premedication. The key is close monitoring — your healthcare team will be checking your blood work regularly to catch problems early.

If you're about to start Amphotericin B therapy, talk with your doctor about which formulation is best for you. The lipid-based formulations (especially AmBisome) have significantly fewer side effects than conventional Amphotericin B Deoxycholate, though they cost more. For information about managing costs or finding Amphotericin B in stock, check out our other guides.