Nerlynx (Neratinib): What to Expect, Side Effects, and More
If you’ve been diagnosed with early-stage, HER2-positive breast cancer and have a very high risk of recurrence even after standard treatment, your doctor may recommend Nerlynx (chemical name: neratinib).
You may be prescribed Nerlynx in combination with the chemotherapy medicine Xeloda (chemical name: capecitabine) if you’ve been diagnosed with advanced-stage or metastatic HER2-positive breast cancer and have been treated with at least two anti-HER2 therapies.
There are several tests used to find out if breast cancer is HER2-positive. Two of the most common tests are:
See Nerlynx prescribing information.
How Nerlynx works
HER2-positive breast cancers make too much of the HER2 protein. The HER2 protein sits on the surface of cancer cells and receives signals that tell the cancer to grow and spread.
Nerlynx fights HER2-positive breast cancer by blocking the cancer cells’ ability to receive growth signals.
What to expect during Nerlynx treatment
Nerlynx is a pill taken by mouth. The recommended dose of Nerlynx is 240 mg (6 tablets) once per day with food.
If you’re taking Nerlynx for early-stage HER2-positive breast cancer, you’ll take the medicine for one year.
If you’re taking Nerlynx for advanced-stage or metastatic breast cancer, you’ll take the medicine with Xeloda for 14 days and then on its own for seven days. This 21-day cycle will be repeated for as long as you’re getting benefits from the medicines and aren’t having severe side effects.
There are certain medicines and foods you should avoid if you are taking Nerlynx:
CYP3A4 inhibitors increase the effects of Nerlynx. This class of medicines includes antifungal medicines such as Onmel (chemical name: itraconazole) and Biaxin (chemical name: clarithromycin), as well as antiretroviral drugs used to treat HIV such as Kaletra (chemical names: lopinavir and ritonavir).
CYP3A inducers decrease the effects of Nerlynx. This class of medicines includes Rifamate (chemical name: rifampin), an antibiotic used to treat tuberculosis, and Carbatrol (chemical name: carbamazepine), which is used to control certain types of seizures in people with epilepsy.
Grapefruit, pomegranate, and juices made from these fruits can increase the effects of Nerlynx.
If you take an antacid medicine, such as a proton pump inhibitor or an H2-receptor antagonist, you should wait three hours after taking the antacid to take Nerlynx. Prilosec, Prevacid, and Nexium are common proton pump inhibitors. Pepcid, Tagamet, and Zantac are common H2-receptor antagonists.
Nerlynx side effects
Like most breast cancer medicines, Nerlynx can cause side effects.
Severe diarrhea is a very common side effect of Nerlynx. In the ExteNET trial, about 40% of the women treated with Nerlynx had severe diarrhea as a side effect.
The FDA approval recommends that loperamide (brand names include Imodium, Kaopectate 1-D, and Pepto Diarrhea Control) be given with Nerlynx for the first 56 days of treatment and then as needed to help manage diarrhea.
Other common side effects of Nerlynx are:
muscle spasms
indigestion
skin changes
In rare cases, Nerlynx may cause serious liver problems. Tell your doctor right away if you have any of the following signs of liver problems:
yellowing of the skin or the whites of the eyes
dark or brown urine
feeling very tired
loss of appetite
pain on the upper right side of the abdomen
bleeding or bruising more easily than normal
Nerlynx can cause embryo death and birth defects. If you’re pregnant or planning to get pregnant, you shouldn't take Nerlynx. You also shouldn’t take Nerlynx while breastfeeding. You should use effective birth control while being treated.
Real patient reviews
Members of our community discuss their experiences with Nerlynx in the community forum. Here are some of their comments. Remember, it's essential to talk to your doctor about any side effects you're having and ask about ways to manage them.
“Today is my 10th day on Nerlynx. So far, I have diarrhea and occasional light nausea. No fatigue. The diarrhea is serious and relentless, but it seems to be getting better in the last two days. For the last week, I have subsisted on oatmeal, bananas, white rice, bread, pasta, and roasted chicken (without the skin), and I drink water, tea, and electrolytes. The diarrhea for me started on day 5. Taking Immodium only.” — laughinggull
“I am 3/4 of the way through my year [taking Nerlynx] now. The diarrhea is a real thing. For me, it’s been a bit of a pendulum and I have to manage the loperamide (Immodium) to best respond…there are dosage instructions for your first few weeks, then you listen to your body. I did months at 1 loperamide (1/2 dose) per day, but my Dr told me to take a break during vacation and when I came back on after 2 weeks, the diarrhea was out of control for months. It’s finally calming down and I am trying to balance my loperamide dose again. Dairy seems to be a trigger so I try to limit that. Otherwise, my main side effect is fatigue — definitely not as bad as chemo, but it is real.” — redkitty815
“I was in the clinical trial years ago. I made it about 4 months. The diarrhea was ridiculous — just constant. They prescribed loperamide to relieve [it], and that did help a little. They also reduced my dosage after a bit. I got dizziness and cold sweats too. I am glad I did it as long as I did though from the outcomes involved.” — geewhiz
Read more in our Nerlynx discussion forum.
Paying for Nerlynx
The cost of Nerlynx may vary. The price you’ll pay depends on the drug manufacturer, your health insurance provider and plan, where you live, and the pharmacy you use.
Note: Your insurance company may require you to get prior authorization before covering Nerlynx.
Learn more about financial assistance and medicine cost-lowering tips.
— Last updated on June 2, 2025 at 3:34 PM
