Bexsero (meningococcal group B) is a vaccine used to prevent meningitis B. Bexsero can cause side effects that range from mild to serious. Examples include injection site redness and pain, muscle aches, and low energy.

Specifically, Bexsero is a biologic vaccine recommended for use in people ages 10–25 years to help prevent meningitis B.

Bexsero comes as a liquid suspension (a type of liquid mixture) in prefilled syringes. It’s given as an injection into your upper arm muscle by a healthcare professional.

Keep reading to learn about the common, mild, and serious side effects Bexsero can cause. See this article for a general overview of the vaccine, including details about its uses.

Some people may experience mild to serious side effects after a Bexsero injection. Examples of the vaccine’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 Bexsero. These include:

In most cases, these side effects last for 3–5 days. And some may be easily managed with over-the-counter medications and home remedies. But if you have ongoing or bothersome symptoms, talk with your doctor or pharmacist.

Bexsero may cause mild side effects other than those listed above. See the vaccine’s prescribing information for details.

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

In rare cases, severe allergic reactions* have been reported with Bexsero. These include sudden swelling of the throat, a drop in blood pressure, and difficulty breathing. It’s best to remain at the vaccine location for 15–30 minutes after your injection for observation by a healthcare professional.

If you develop a severe allergic reaction after receiving Bexsero, 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 vaccine, it and the Centers for Disease Control and Prevention (CDC) track side effects of the drug. If you’d like to report a side effect you’ve had with Bexsero, visit the Vaccine Adverse Event Reporting System (VAERS) website.

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

How long do side effects of Bexsero typically last?

The CDC says that side effects of Bexsero may last for 3–5 days and usually resolve on their own. If you have side effects that are bothersome or ongoing, talk with your doctor or pharmacist.

Does Bexsero cause long-term side effects?

It’s unlikely. Long-term side effects weren’t reported in studies of Bexsero. Talk with your doctor or pharmacist if you’re concerned about possible long-term side effects from Bexsero.

How do side effects of Bexsero compare with those of Trumenba?

Bexsero and Trumenba are both meningococcal group B vaccines made by different companies. reports that each vaccine has the same side effects. Examples include injection site reactions, fatigue, headache, and muscle pain.

If you have questions about choosing a meningococcal group B vaccine, talk with your pharmacist or doctor.

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

Injection site reactions

Injection site reactions were a common side effect reported in studies of Bexsero. Rarely, a reaction may cause swelling from shoulder to elbow.

It’s important to note that an injection site reaction isn’t considered an allergic reaction. So it won’t prevent you from being able to get vaccines in the future. Reactions may also occur with booster shots of Bexsero.

Symptoms of injection site reactions include:

  • pain
  • red or discolored skin
  • fever for 24 hours or less
  • swelling
  • hardened lump at the injection site that can last for more than 1 month
  • blisters near the injection site

Factors that can increase the risk of injection site reactions with this vaccine include:

  • incorrect arm positioning
  • injection of cold vaccine
  • history of sensitivity to vaccine ingredients

What might help

To help lower your chance of injection site reactions from Bexsero, consider:

  • informing your doctor or pharmacist about any previous vaccine sensitivities
  • completely removing the arm from clothing or loosening clothing above the injection site
  • relaxing your arm and hanging it by your side
  • avoiding forcefully rubbing the injection site

The purpose of a vaccine is to trigger an immune system response. So even if you have no sensitivities and position your arm correctly, you may still have a reaction at the injection site.

If you develop an injection site reaction, you can help relieve your symptoms by using over-the-counter medications or home remedies. You can try:

  • applying a cool compress to the site
  • regularly moving the arm to help drain fluid
  • taking acetaminophen for pain relief

Talk with your doctor or pharmacist if you develop a fever or severe symptoms lasting longer than 24 hours. These symptoms include:

They’ll likely recommend that you have a medical evaluation.

Fainting after injection

Fainting was a common side effect reported in studies of Bexsero. Fainting may cause symptoms such as:

  • loss of consciousness
  • muscle twitching or jerking
  • confusion
  • pale yellow or gray skin
  • sweating
  • low heart rate
  • dizziness or lightheadedness
  • nausea
  • vomiting

A common cause of fainting is vasovagal response. This happens when your body overreacts to specific triggers, such as stress, fear, pain, or the sight of blood. This overreaction causes your heart rate and blood pressure to drop suddenly, leading to less blood flow to your brain, which can make you faint.

What might help

To lower the chance of fainting and injuring yourself, sit or lie down while being vaccinated and for up to 15 minutes afterward. Eating 1–2 hours before you receive a vaccine and staying hydrated is also important.

Most people who faint recover in a few minutes. But if you faint during a vaccination, it’s necessary to remain under the observation of a healthcare professional until you feel better. Vaccinators are trained to monitor you, respond if you’re distressed, and call 911 (or your local emergency number) if your condition worsens.

Allergic reaction

As with most vaccines, allergic reactions can happen in some people who receive Bexsero, according to studies. 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 oral antihistamine, 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 Bexsero, they’ll decide if you should receive it again.

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 Bexsero, they may have you switch to a different option.

Keeping track of side effects

After your Bexsero vaccine, consider taking notes on any side effects you have. You can then share this information with your doctor. This is especially helpful when you receive the first dose of the Bexsero vaccine series.

Your side effect notes can include things such as:

  • how soon you had the side effect after receiving Bexsero
  • 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 Bexsero affects you. They can then use this information to adjust your treatment plan if needed.

Below is important information you should consider before receiving Bexsero.


Bexsero can sometimes cause harmful effects in people with certain conditions. Other factors may also affect whether this vaccine is a good option for you. Talk with your doctor about your health history before receiving a Bexsero injection. Be sure to tell them if any of the following factors apply to you:

Alcohol and Bexsero

There are no known interactions between alcohol and Bexsero. If you have questions about consuming alcohol after receiving a Bexsero injection, talk with your doctor or pharmacist.

Pregnancy and breastfeeding with Bexsero

There’s limited information about the safety of the Bexsero vaccine when received during pregnancy.


It’s not known whether it’s safe to receive Bexsero during pregnancy. There isn’t enough information from studies about the risks of the vaccine in pregnant people. If you’re pregnant or planning to become pregnant, talk with your doctor before receiving Bexsero.

The CDC recommends that pregnant people wait to get the meningococcal B vaccine. But if you’re at higher risk, talk with your doctor to decide if the vaccine’s benefits outweigh the possible risks.

High risk individuals include:

  • people between 16 and 23 years of age
  • those traveling to places with a higher occurrence of meningitis B
  • people living in a group setting
  • scientists researching N. meningitidis bacteria
  • individuals with a weakened immune system
  • those recently exposed to someone who has meningitis B

If you receive this vaccine while pregnant, consider signing up for the Bexsero pregnancy registry by visiting the website or calling 877-413-4759. A pregnancy registry collects information about the safety of certain drugs and vaccines when used during pregnancy.


It’s not known whether the Bexsero vaccine is safe to receive while breastfeeding. Scientists aren’t sure if parts of Bexsero pass into breast milk. And there isn’t enough research to tell us what effects this vaccine might have on milk production or a child who’s breastfed.

If you’re breastfeeding or planning to do so, talk with your doctor before getting vaccinated with Bexsero.

Like most vaccines, Bexsero can cause some side effects that range from mild to serious. But most are temporary and go away after a few days to weeks. If you have questions about side effects this vaccine can cause, talk with your doctor. Examples to help get you started include:

  • Can Bexsero cause meningitis B?
  • Can I get the second dose of Bexsero if my arm swelled with the first one?
  • What side effects of Bexsero should alert me to contact you?
  • How can I manage any side effects of Bexsero I may have?

To learn more about Bexsero, see these articles:

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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.