What You Should Know About Tacrolimus Side Effects

Tacrolimus is a life-saving immunosuppressant used primarily to prevent organ rejection after transplant surgery. But like all powerful medications, it comes with side effects — some common and manageable, others serious enough to require immediate medical attention.

This guide covers what to expect when taking Tacrolimus, which side effects are normal, and when you should call your doctor. Knowing the difference can help you stay safe while getting the most benefit from your treatment.

What Is Tacrolimus?

Tacrolimus (brand names Prograf, Envarsus XR, Astagraf XL) is a calcineurin inhibitor that suppresses your immune system to prevent it from attacking a transplanted organ. It's FDA-approved for kidney, liver, and heart transplant recipients. A topical form (Protopic) is used for atopic dermatitis. For a full overview, see our complete guide to Tacrolimus.

Common Side Effects

These side effects are reported frequently in clinical trials and are often manageable with time or dose adjustments. Tell your doctor about any of these, but they don't usually require emergency care:

• Tremors — One of the most common side effects. You may notice shaking in your hands, especially early in treatment. This often improves as your body adjusts or your dose is lowered.
• Headache — Frequent, especially in the first few weeks. Over-the-counter pain relievers may help, but check with your doctor first since some interact with Tacrolimus.
• Diarrhea — Can range from mild to significant. Stay hydrated and let your doctor know if it persists.
• Nausea — Taking Tacrolimus with food (consistently) may help reduce stomach upset.
• High blood pressure — Your doctor will monitor this regularly. You may need blood pressure medication.
• Kidney function changes — Increased creatinine levels are common. Your doctor monitors kidney function through regular blood tests.
• High blood sugar — Tacrolimus can raise blood glucose levels and may even cause new-onset diabetes after transplant (NODAT). Regular blood sugar monitoring is important.
• High potassium levels (hyperkalemia) — Usually caught on routine blood work. Your doctor may adjust your diet or medications.
• Low magnesium levels — May cause muscle cramps or weakness. Supplements may be prescribed.
• Insomnia — Difficulty sleeping is reported by many patients.
• Hair loss — Some patients experience thinning hair.
• Abdominal pain — Stomach discomfort or cramping may occur.

Serious Side Effects — When to Call Your Doctor

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

Kidney Damage (Nephrotoxicity)

Tacrolimus can damage the kidneys, especially at higher blood levels. Signs include significantly decreased urine output, swelling in your legs or feet, and unexplained weight gain. This is one reason regular blood tests are so important — your doctor needs to keep Tacrolimus at the right level to protect your transplant without harming your kidneys.

Nervous System Problems (Neurotoxicity)

In rare cases, Tacrolimus can cause seizures or a condition called posterior reversible encephalopathy syndrome (PRES). Warning signs include severe headache, confusion, vision changes, and seizures. Seek emergency care immediately.

Severe Infections

Because Tacrolimus suppresses your immune system, you're at higher risk for infections — including BK virus, CMV (cytomegalovirus), and other opportunistic infections. Call your doctor if you develop a fever, persistent cough, painful urination, or any signs of infection that aren't getting better.

Increased Cancer Risk

Long-term immunosuppression with Tacrolimus increases the risk of lymphoma and skin cancers. Wear sunscreen, avoid tanning beds, and report any unusual skin changes or lumps to your doctor. Regular skin checks are recommended.

Heart Rhythm Changes (QT Prolongation)

Tacrolimus can affect your heart rhythm. Seek immediate care if you experience rapid or irregular heartbeat, dizziness, or fainting.

Gastrointestinal Perforation

Rarely, Tacrolimus can cause a hole in the stomach or intestines. Seek emergency care for severe abdominal pain, especially with fever.

Specific Populations at Higher Risk

Some patients need extra monitoring while taking Tacrolimus:

• Patients with liver problems — May need lower doses because Tacrolimus is processed by the liver. Higher blood levels increase side effect risk.
• African-American patients — May require higher doses to achieve target blood levels, which can increase the risk of dose-related side effects.
• Patients with kidney problems — Since Tacrolimus can damage kidneys, patients with pre-existing kidney issues need especially careful monitoring.
• Pregnant patients — Tacrolimus crosses the placenta and may cause harm to the baby. However, transplant patients may need to continue therapy. Your transplant team and OB/GYN should work together closely.
• Breastfeeding patients — Tacrolimus is excreted in breast milk. Breastfeeding is generally not recommended while taking it.

How to Manage Side Effects

Here are practical steps to help manage the most common side effects:

Stay on Top of Blood Work

This is the single most important thing you can do. Regular trough level monitoring lets your doctor fine-tune your dose to minimize side effects while keeping your transplant safe. Don't skip lab appointments.

Take Your Medication Consistently

Take Tacrolimus at the same times every day. For immediate-release capsules, that means approximately 12 hours apart. For extended-release (Envarsus XR or Astagraf XL), once daily in the morning. Consistency helps maintain steady blood levels.

Avoid Grapefruit

Grapefruit and grapefruit juice can significantly increase Tacrolimus levels in your blood, raising the risk of side effects. Avoid them completely. For more on food and drug interactions, see our dedicated guide.

Monitor Your Blood Sugar

If you notice increased thirst, frequent urination, or blurry vision, let your doctor know — these can be signs of high blood sugar or new-onset diabetes.

Protect Your Skin

Use sunscreen (SPF 30+) daily, wear protective clothing, and see a dermatologist annually for skin cancer screening.

Stay Hydrated

Drink plenty of water, especially if you're experiencing diarrhea. Dehydration can worsen kidney function and affect Tacrolimus levels.

Talk to Your Doctor Before Taking Anything New

Even over-the-counter medications and supplements can interact with Tacrolimus. Always check before starting anything new, including herbal remedies and NSAIDs like ibuprofen.

Final Thoughts

Tacrolimus side effects range from common inconveniences like tremors and headaches to serious concerns like kidney damage and increased infection risk. The key to staying safe is regular monitoring, consistent dosing, and open communication with your transplant team.

Don't stop taking Tacrolimus without your doctor's guidance — the risk of organ rejection is far more dangerous than most side effects. If cost or availability is making it hard to stay on your medication, Medfinder can help you find Tacrolimus in stock at a pharmacy near you.