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

What You Need to Know About Vancomycin Side Effects

Vancomycin is a glycopeptide antibiotic used to fight serious bacterial infections caused by gram-positive bacteria, including MRSA and Clostridioides difficile (C. diff). It is available as an IV infusion for systemic infections and as oral capsules or solution for C. diff infections.

Like all antibiotics, Vancomycin can cause side effects. Some are mild and manageable, while others are serious and require immediate medical attention. This guide covers what to expect and when to call your doctor.

What Is Vancomycin?

Vancomycin is a powerful antibiotic that works by blocking bacteria from building their cell walls, which kills the bacteria. It has been in use since the late 1950s and remains a critical drug for treating drug-resistant infections. For a complete overview, see our guide on what Vancomycin is and how it is used.

Common Side Effects

These side effects occur frequently and are usually mild. They often improve as your body adjusts to the medication or after treatment ends:

• Nausea and vomiting — Especially common with oral Vancomycin. Taking it with food may help, though it can be taken with or without food.
• Abdominal pain — Stomach discomfort and cramping are common, particularly with the oral form.
• Diarrhea — Mild diarrhea is common during antibiotic therapy. However, if diarrhea becomes severe or bloody, contact your doctor immediately (see serious side effects below).
• Headache — A frequent but usually mild side effect.
• Back pain — Some patients experience back pain during or after IV infusions.
• Fever — Low-grade fever can occur as a side effect of treatment.
• Phlebitis at the IV site — Redness, swelling, or pain where the IV needle is inserted. This is common with IV Vancomycin and can often be managed by slowing the infusion rate or changing the IV site.

Red Man Syndrome

One of the most well-known side effects of Vancomycin is Red Man Syndrome (also called Vancomycin Flushing Syndrome). This is not a true allergy — it is caused by the release of histamine when Vancomycin is infused too quickly.

Symptoms include:

• Red flushing of the face, neck, and upper body
• Itching and rash
• Low blood pressure
• Sometimes chest pain or muscle spasms

How to prevent it: Red Man Syndrome is almost always preventable by infusing Vancomycin slowly — over at least 60 minutes (or longer for larger doses). Your healthcare team will manage the infusion rate. If it happens, the infusion will be stopped and restarted at a slower rate, sometimes with an antihistamine like Diphenhydramine (Benadryl) given beforehand.

Serious Side Effects

These side effects are less common but can be dangerous. Contact your doctor or seek emergency care if you experience any of the following:

Nephrotoxicity (Kidney Damage)

Vancomycin can damage the kidneys, especially at higher doses, during prolonged treatment, or when combined with other kidney-toxic drugs like Aminoglycosides or Amphotericin B. Signs include:

• Decreased urine output
• Swelling in your legs or ankles
• Unusual fatigue

Your doctor will monitor your kidney function with regular blood tests (BUN and creatinine) during treatment.

Ototoxicity (Hearing Damage)

Vancomycin can cause hearing loss or tinnitus (ringing in the ears), particularly in patients who also take other ototoxic drugs like Aminoglycosides, Cisplatin, or loop diuretics (Furosemide). Tell your doctor immediately if you notice:

• Ringing or buzzing in your ears
• Difficulty hearing
• A feeling of fullness in your ears

Severe Allergic Reactions

True allergic reactions to Vancomycin are rare but can include:

• Anaphylaxis (difficulty breathing, swelling of the face/throat, severe drop in blood pressure)
• Stevens-Johnson Syndrome (SJS) or Toxic Epidermal Necrolysis (TEN) — severe skin reactions with blistering and peeling
• DRESS Syndrome (Drug Reaction with Eosinophilia and Systemic Symptoms) — fever, rash, swollen lymph nodes, and organ involvement

Seek emergency medical care immediately if you experience any of these reactions.

Blood Cell Changes

• Thrombocytopenia — A drop in platelet count, which can cause unusual bruising or bleeding.
• Neutropenia — A drop in white blood cells, which can increase infection risk. This is more common with prolonged courses of Vancomycin (longer than 2 weeks).

Superinfection

Ironically, IV Vancomycin can sometimes cause C. difficile-associated diarrhea as a superinfection. If you develop watery or bloody diarrhea during or after IV Vancomycin treatment, tell your doctor right away.

Special Populations

Certain groups of people may be at higher risk for side effects:

• Older adults — Higher risk of kidney damage and hearing loss. Doses may need to be lower and monitoring more frequent.
• People with kidney problems — Vancomycin is cleared by the kidneys, so impaired kidney function leads to higher drug levels and increased risk of toxicity. Dose adjustments are required.
• Pregnant women — Vancomycin is Pregnancy Category C. It should be used only when the benefits clearly outweigh the risks. Discuss with your doctor.
• Children and newborns — Dosing is based on weight and age. Careful monitoring is required.
• Obese patients — Initial dosing uses actual body weight, but close monitoring of blood levels is essential to avoid toxicity.

How to Manage Side Effects

Here are practical tips for managing common Vancomycin side effects:

• For nausea: Eat small, bland meals. Avoid greasy or spicy foods during treatment.
• For diarrhea: Stay hydrated. Drink plenty of water and electrolyte-containing fluids. If diarrhea is severe or contains blood, stop taking the medication and call your doctor.
• For IV site pain: Tell your nurse so they can slow the infusion rate or change the site. Warm compresses may help.
• For Red Man Syndrome: This is managed by your healthcare team. They may slow the infusion or give you an antihistamine before your next dose.
• Keep all monitoring appointments: Regular blood tests for kidney function and drug levels are essential to catch problems early.

Never stop taking Vancomycin early without talking to your doctor, even if you feel better. Stopping antibiotics too soon can allow the infection to come back stronger.

Final Thoughts

Vancomycin is a critical antibiotic for serious infections, and most patients tolerate it well with proper monitoring. The most important things to watch for are kidney function changes, hearing problems, and signs of an allergic reaction.

Talk to your doctor about any side effects you experience during treatment. If you are having trouble finding Vancomycin at your pharmacy, Medfinder can help you locate it in stock near you.