Takhzyro (lanadelumab-flyo) is a prescription drug that helps prevent severe swelling attacks caused by hereditary angioedema (HAE). Takhzyro can cause side effects that range from mild to serious. Examples include injection site reactions and upper respiratory infection.

Takhzyro is used in adults and in children ages 2 years and older to prevent attacks caused by HAE. This is a genetic (inherited) condition that causes severe swelling attacks. The swelling most often affects the face, hands, and feet.

The active ingredient in Takhzyro is lanadelumab-flyo.* (An active ingredient is what makes a drug work.) Takhzyro is a biologic medication, which means it’s made from parts of living cells.

Takhzyro comes as a liquid solution in a pre-filled syringe or vial. You’ll inject the drug under your skin.

Keep reading to learn about the common, mild, and serious side effects that Takhzyro can cause. For a general overview of the drug, including details about its uses, see this article.

* The reason “-flyo” appears at the end of the drug’s name is to show that the drug is distinct from similar medications that may be created in the future.

Some people may experience mild to serious side effects during their Takhzyro treatment. Examples of Takhzyro’s commonly reported side effects include:

* To learn more about this side effect, see the “Side effects explained” section below.

Mild side effects have been reported with Takhzyro. These include:

* To learn more about this side effect, see the “Side effects explained” section below.

In most cases, these side effects should be temporary. And some may be easily managed. But if you have any symptoms that are ongoing or bother you, talk with your doctor or pharmacist. And don’t stop using Takhzyro unless your doctor recommends it.

Takhzyro may cause mild side effects other than the ones listed above. See the drug’s prescribing information for details.

Serious side effects have been reported with Takhzyro, but these are rare. Serious side effects that may occur include:

If you develop serious side effects while taking Takhzyro, call your doctor right away. If the side effects seem life threatening or you think you’re having a medical emergency, immediately call 911 or your local emergency number.

* To learn more about this side effect, see the “Side effects explained” section below.

Note: After the Food and Drug Administration (FDA) approves a drug, it tracks side effects of the medication. If you’d like to notify the FDA about a side effect you’ve had with Takhzyro, visit MedWatch.

Get answers to some frequently asked questions about Takhzyro’s side effects.

Does Takhzyro cause different side effects in children than in adults?

No, Takhzyro’s side effects are the same among children and adults. In studies of the drug, no different side effects were reported in children 2 to 12 years old than in adults using the drug. (Takhzyro is used in children ages 2 years and older.)

If you have other questions or concerns about Takhzyro’s side effects, talk with your doctor or your child’s doctor.

How do the side effects of Takhzyro and icatibant acetate (Firazyr) compare?

Takhzyro and Firazyr have some similar side effects and others that vary.

Both drugs are used in people with hereditary angioedema, but for different purposes. They both come as a liquid solution that’s given as an injection under the skin. The most common side effect in people using either Takhyzro or Firazyr is an injection site reaction.

To learn more about Firazyr’s side effects, see this article. Your doctor can also tell you more about how the side effects of these two drugs compare.

Learn more about some of the side effects Takhzyro may cause.

Upper respiratory infection

Some people may have an upper respiratory infection such as the common cold during their Takhzyro treatment.

The common cold was the second-most common side effect reported in Takhzyro’s studies. Symptoms of a cold may include:

  • runny nose
  • sneezing
  • sore throat
  • coughing

What might help

To help prevent an upper respiratory infection while using Takhzyro, avoid being in close contact with people who are sick. In addition, wash your hands regularly.

If you do develop a cold or other infection and your symptoms worsen or don’t go away, talk with your doctor.

Injection site reactions

Takhzyro can cause injection site reactions, which are reactions at the site where you’ve injected the drug. This was a common side effect reported in studies of Takhzyro.

Examples of injection site reactions include:

  • pain
  • bruising
  • warmth
  • discoloration (such as redness)
  • itchiness
  • burning or a prickling sensation

Symptoms of a serious injection site reactions include severe bleeding or bruising.

What might help

If you have an injection site reaction while using Takhzyro, talk with your doctor. If you think your reaction is severe, get medical care right away and let your doctor know.

The treatment your doctor recommends will depend on your specific reaction. For example, your doctor may suggest a steroid cream such as hydrocortisone to help reduce swelling, discoloration, and itchiness. If the reaction is mild, a cold compress may also help. For pain, your doctor may suggest an over-the-counter pain reliever such as acetaminophen (Tylenol).

If you have repeated injection site reactions after using Takhzyro, talk with your doctor. But you should not stop using Takhzyro without talking with your doctor first. Your condition can worsen without treatment.


Takhzyro can cause headache in some people. This may include a tension headache or sinus headache. In studies of the Takhzyro, headache was a common but mild side effect.

With a tension headache, you may have pain in the head, neck, or behind the eyes. A sinus headache may cause pain or pressure in the eyes, cheeks, nose, and forehead.

What might help

To treat headache from Takhzyro, you can take an over-the-counter pain reliever such as acetaminophen (Tylenol). If your headache doesn’t go away or gets worse, talk with your doctor.

Allergic reaction

Like most drugs, Takhzyro can cause an allergic reaction in some people.

Symptoms can be mild to serious and can include:

  • skin rash
  • itchiness
  • flushing (temporary warmth, redness, or deepening of skin color)
  • swelling under your skin, usually in your eyelids, lips, hands, or feet
  • swelling of your mouth, tongue, or throat, which can make it hard to breathe

What might help

If you have mild symptoms of an allergic reaction, such as a mild rash, call your doctor right away. They may suggest a treatment to manage your symptoms. Examples include:

  • an antihistamine you swallow, such as Benadryl (diphenhydramine)
  • a product you apply to your skin, such as hydrocortisone cream

If your doctor confirms you’ve had a mild allergic reaction to Takhzyro, they’ll decide if you should continue using it.

If you have symptoms of a severe allergic reaction, such as swelling or trouble breathing, call 911 or your local emergency number right away. These symptoms could be life threatening and require immediate medical care.

If your doctor confirms you’ve had a serious allergic reaction to Takhzyro, they may have you switch to a different treatment.

Keeping track of side effects

During your Takhzyro treatment, consider taking notes on any side effects you’re having. You can then share this information with your doctor. This is especially helpful when you first start taking a new drug or using a combination of treatments.

Your side effect notes can include things such as:

  • what dose of the drug you were taking when you had the side effect
  • how soon you had the side effect after starting that dose
  • what your symptoms were
  • how your symptoms affected your daily activities
  • what other medications you were taking
  • any other information you feel is important

Keeping notes and sharing them with your doctor will help them learn more about how Takhzyro affects you. They can then use this information to adjust your treatment plan if needed.

Takhzyro may not be right for you if you have certain medical conditions. These are known as drug-condition interactions. Other factors may also affect whether Takhzyro is a good treatment option for you.

Talk with your doctor about your health history before starting Takhzyro. Factors to consider include those described below.

Allergic reaction. If you’ve had an allergic reaction to Takhzyro or any of its ingredients, your doctor will likely not prescribe Takhzyro. Ask them what other medications are better options for you.

Alcohol and Takhzyro

There’s no known interaction between Takhzyro and alcohol.

If you drink alcohol, talk with your doctor about how much may be safe to drink during your Takhzyro treatment.

Pregnancy and breastfeeding while using Takhzyro

It’s unknown whether Takhzyro is safe to use while pregnant. The drug’s use during pregnancy hasn’t been studied. But monoclonal antibodies (the group of drugs Takhzyro belongs to) pass through the placenta during the third trimester of pregnancy. So, it’s thought that the risk of negative effects from Takhyzro may be higher if taken during the third trimester.

It’s also not known whether Takhzyro is safe to use while breastfeeding. But it’s possible that the drug may pass into breast milk.

If you’re pregnant or breastfeeding, or planning to become pregnant or to breastfeed, talk with your doctor before using Takhzyro.

If you still have questions about side effects that Takhzyro can cause, talk with your doctor. Examples of questions that you may want to ask include:

  • Does Takhzyro cause hair loss?
  • Do I have a higher risk of side effects with Takhzyro if I’m age 65 years or older?
  • How do the side effects of Takhzyro compare with those of Cinryze?

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Disclaimer: Healthline has made every effort to make certain that all information is factually correct, comprehensive, and up to date. However, this article should not be used as a substitute for the knowledge and expertise of a licensed healthcare professional. You should always consult your doctor or another healthcare professional before taking any medication. The drug information contained herein is subject to change and is not intended to cover all possible uses, directions, precautions, warnings, drug interactions, allergic reactions, or adverse effects. The absence of warnings or other information for a given drug does not indicate that the drug or drug combination is safe, effective, or appropriate for all patients or all specific uses.