Understanding Potential Risks

What is the most important information I should know about ENHERTU?

ENHERTU can cause serious side effects

Some serious or life-threatening side effects may affect your lungs, heart, or white blood cell count, affecting your ability to fight infection.

Your healthcare provider will check you for these side effects during your treatment with ENHERTU. Your healthcare provider may reduce your dose, delay treatment, or completely stop treatment with ENHERTU if you have severe side effects

Pay special attention to and notify your healthcare provider of new or worsening symptoms as they may be related to:

Tell your healthcare provider right away if you get any of the following signs and symptoms:
  • Cough
  • Trouble breathing or shortness of breath
  • Fever
  • Other new or worsening breathing symptoms (e.g., chest tightness, wheezing)

If you develop lung problems, your healthcare provider may treat you with corticosteroid medicines.

  • Low white blood cell counts are common with ENHERTU and can sometimes be severe
  • Your healthcare provider will check your white blood cell counts before starting ENHERTU and before starting each dose
  • Tell your healthcare provider right away if you develop any signs or symptoms of an infection or have fever or chills during treatment with ENHERTU

Your healthcare provider will check your heart function before starting treatment with ENHERTU.

Tell your healthcare provider right away if you develop any of the following signs and symptoms:

  • New or worsening shortness of breath
  • Coughing
  • Feeling tired
  • Swelling of your ankles or legs
  • Irregular heartbeat
  • Sudden weight gain
  • Dizziness or feeling light-headed
  • Loss of consciousness

Tell your healthcare provider right away if you become pregnant or think you might be pregnant during treatment with ENHERTU

  • If you are able to become pregnant, your healthcare provider should do a pregnancy test before you start treatment with ENHERTU
  • Females who are able to become pregnant should use effective birth control (contraception) during treatment with ENHERTU and for 7 months after the last dose
  • Males who have female partners that are able to become pregnant should use effective birth control (contraception) during treatment with ENHERTU and for 4 months after the last dose

Will my healthcare provider adjust my dose if I have side effects?

To help manage side effects, your healthcare provider may:

Reduce your dose

Delay your dose

Stop ENHERTU

  • Your healthcare provider will give you medicines before your infusion to help prevent nausea and vomiting
  • If you miss a planned dose of ENHERTU, call your provider right away to schedule an appointment. Do not wait until the next planned treatment cycle.

Talk to your healthcare provider about help with
some side effects

Useful tips to help you manage some of these side effects:

  • Try to eat 5 or 6 small meals and snacks each day instead of 3 large meals
  • Have bland, easy-to-digest food and drinks
  • Avoid food and drinks that are too hot or too cold
  • Avoid strong smells if possible
  • If you are vomiting, take deep, slow breaths or get fresh air

Talk to your healthcare provider about these tips and
before taking any medicine for nausea

  • Try to eat 5 or 6 small meals and snacks each day instead of 3 large meals
  • Eat foods low in fiber
  • Drink clear liquids to replace lost fluids. Check with your healthcare provider for how much fluid you should drink and what types of fluid might be best for you

Talk to your healthcare provider about these tips and
before taking any medicine for diarrhea

  • Try activities such as meditation, which helps with relaxation and decreases stress
  • Plan rest time and try not to do too much
  • Try to get regular exercise during times when your energy level is high (according to your healthcare provider’s approval)

Talk to your healthcare provider to help determine
the cause of why you may be feeling tired

Before hair loss:

  • Talk to your healthcare provider about the possibility of hair loss
  • Consider cutting your hair short to feel more in control of hair loss
  • Be gentle when you wash your hair. Use a mild shampoo, such as baby shampoo
  • Avoid items such as electric hair dryers, hairspray, hair dyes, products to perm or relax your hair, hair bands and clips that can hurt your scalp
  • If you plan on buying a wig, you should do so while you still have hair

If hair loss occurs:

  • Protect your scalp
  • Cover your head to help stay warm. You may feel colder once you lose your hair
  • Sleeping on a satin pillowcase. Satin creates less friction and may be more comfortable

Talk to your healthcare provider about these tips and
before taking any medicine for hair loss

What are the possible side effects of ENHERTU?

ENHERTU can cause serious side effects. See "What is the most important information I should know about ENHERTU?" above.

The most common side effects of ENHERTU when used in people with HER2-positive gastric or GEJ adenocarcinoma, include:

  • Low red blood cell counts
  • Low white blood cell counts
  • Low platelet counts
  • Nausea
  • Decreased appetite
  • Increased liver function tests
  • Feeling tired
  • Diarrhea
  • Low levels of blood potassium
  • Vomiting
  • Constipation
  • Fever
  • Hair loss

ENHERTU may cause fertility problems in males, which may affect the ability to father children. Talk to your healthcare provider if you have concerns about fertility.

These are not all of the possible side effects of ENHERTU. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.

Before you receive ENHERTU, tell your healthcare provider about all of your medical conditions, including if you:

  • Have lung or breathing problems.
  • Have kidney problems. Your healthcare provider may follow you more closely. in clinical trials, more serious lung problems were seen in patients with certain kidney problems.
  • Have liver problems. Your healthcare provider may follow you more closely.
  • Have signs or symptoms of an infection.
  • Have or have had any heart problems.
  • Are breastfeeding or plan to breastfeed. It is not known if ENHERTU passes into your breast milk. Do not breastfeed during treatment with ENHERTU and for 7 months after the last dose.

Tell your healthcare provider about all the medicines you take, including prescription and over-the-counter medicines, vitamins, and herbal supplements.

Harm to your unborn baby. Tell your healthcare provider right away if you become pregnant or think you might be pregnant during treatment with ENHERTU.

  • If you are able to become pregnant, your healthcare provider should do a pregnancy test before you start treatment with ENHERTU.
  • Females who are able to become pregnant should use effective birth control (contraception) during treatment with  ENHERTU and for 7 months after the last dose.
  • Males who have female partners that are able to become pregnant should use effective birth control (contraception) during treatment with ENHERTU and for 4 months after the last dose.

Talk to your doctor before taking any
medications or making changes to your diet or daily activities

Downloadable Resources for Patients and Care Partners

Understanding and
managing side effects during
treatment with ENHERTU

Helping you communicate
with healthcare providers not
involved with your ENHERTU
treatment