What Are the Side Effects of Amphotericin B?

The initial “induction” phase of treating cryptococcosis typically lasts just one to two weeks, but it is intense ^[1]. During this time, you are likely receiving a powerful intravenous (IV) antifungal medication called Amphotericin B, often given alongside another drug called flucytosine ^[1]. Amphotericin B is notorious for causing harsh side effects—so much so that medical professionals and patients sometimes refer to it as “Ampho-terrible.” If this medication is making you feel awful, your experience is completely valid and, unfortunately, very common.

The most significant side effects of conventional Amphotericin B are nephrotoxicity (kidney injury) and severe drops in essential electrolytes like potassium and magnesium ^[2][3]. It can also cause a significant drop in red blood cells (anemia), severe vein irritation, and intense infusion reactions like chills and fever ^[4][5]. Fortunately, doctors anticipate these toxicities and use specific, proactive strategies to manage them and protect your body ^[6].

How the Care Team Protects Your Kidneys

Because Amphotericin B is harsh on the kidneys, your care team will not simply wait for side effects to appear:

• Aggressive Hydration: Before giving you the medication, nurses will typically administer at least a liter of intravenous normal saline (saltwater) ^[6]. Flushing the kidneys with extra fluids before and after the dose helps protect the delicate renal tissue.
• Electrolyte Replacements: Amphotericin B causes the kidneys to waste essential minerals ^[3]. To prevent dangerously low levels (hypokalemia for potassium and hypomagnesemia for magnesium), you will usually receive daily IV or oral supplements ^[7][8].
• Daily Bloodwork: Your doctors will check your blood every single day to monitor your creatinine (a marker of kidney function) and your electrolyte levels ^[9]. If your numbers start moving in the wrong direction, they can adjust your fluids, pause the medication, or switch to an alternative.

A Note on Reversibility and Pain: It is completely understandable to fear permanent organ damage. However, the kidney injury caused by Amphotericin B is typically reversible, and your kidney function will usually recover after the medication is stopped ^[9][2]. Additionally, while “nephrotoxicity” shows up on your lab results, actual physical pain in your kidney area (your mid-to-lower back or flank) is not a standard side effect. If you are feeling physical kidney pain, page your nurse immediately, as it is a red flag that requires prompt medical evaluation.

The “Liposomal” Alternative

If you are wondering why your doctors didn’t start with a safer option, it often comes down to hospital formulary availability and high costs ^[10][6]. Conventional Amphotericin B (Amphotericin B deoxycholate) is inexpensive and widely available, but if it is causing too much kidney damage, there is another option.

Liposomal Amphotericin B (often known by the brand name AmBisome) is the exact same active drug, but it is packaged inside a microscopic bubble of fat (a liposome) ^[11]. This lipid coating changes how the drug travels through your body, allowing it to reach the fungal infection effectively while shielding your kidneys from the harshest toxicities ^[6][12]. Studies show that patients receiving the liposomal version experience significantly less kidney damage, fewer severe electrolyte drops, and less anemia ^[6][13]. If you are struggling with the conventional version, asking your doctor about switching to liposomal Amphotericin B is an excellent next step.

Other Common Side Effects

Beyond your kidneys, you may experience:

• Infusion Reactions: You might experience shaking chills (often called “rigors”), fever, nausea, or headaches while the drug is infusing or shortly after. These reactions often decrease in intensity after the first few doses ^[6]. If the shaking chills become severe, nurses can give you strong medications like meperidine (Demerol) or morphine to stop them quickly and make you more comfortable ^[14].
• Anemia: Both Amphotericin B and the flucytosine pills you are likely taking alongside it can suppress your bone marrow’s ability to make red blood cells, leading to severe fatigue and weakness ^[4]. Your care team will monitor your hemoglobin levels daily and can provide a blood transfusion if your levels drop too low ^[6].
• Vein Irritation (Phlebitis): Conventional Amphotericin B can be incredibly irritating to small peripheral veins in your arms ^[6]. Because of this, your care team may recommend placing a specialized, larger IV line (like a PICC line or central line) to make the infusions pain-free and protect your blood vessels.

Remember, the heavy induction phase is temporary. Once the fungal infection is knocked down, you will likely be transitioned off the IV medications and onto gentler oral medications, such as fluconazole, for the remainder of your treatment ^[6].