Perjeta: Side Effects, How it Works, and More
If you’ve been diagnosed with metastatic, HER2-positive breast cancer and you haven’t received anti-HER2 therapy or chemotherapy for metastatic breast cancer in the past, your doctor may recommend Perjeta.
Perjeta (chemical name: pertuzumab) is used in two chemo regimens:
THP, which consists of Herceptin (chemical name: trastuzumab), another targeted therapy medicine, and Taxol (chemical name: paclitaxel) or Taxotere (chemical name: docetaxel), a type of chemotherapy.
TCHP is similar to THP, but with the addition of carboplatin (brand name: Paraplatin), a chemotherapy medication.
Your doctor may also recommend Perjeta if you have:
HER2-positive, locally advanced, inflammatory, or early-stage breast cancer (tumor is greater than 2 cm in diameter or node-positive)
HER2-positive early breast cancer that has a high likelihood of coming back
See Perjeta prescribing information.
How Perjeta works
Perjeta works by attaching itself to the HER2 receptors on the surface of breast cancer cells and blocking them from receiving growth signals. Perjeta targets a different area of the HER2 receptor than Herceptin does, so it’s believed to work in a complementary way. By blocking the signals, Perjeta can slow or stop the growth of the breast cancer.
In addition to blocking HER2 receptors, Perjeta can also help fight breast cancer by alerting the immune system to destroy cancer cells.
There are several tests used to find out if breast cancer is HER2-positive. Two of the most common tests are:
What to expect during Perjeta treatment
Perjeta is prescribed with Herceptin, another targeted therapy medicine, and chemotherapy. All these medicines may be given intravenously, which means they’re delivered directly into your bloodstream through an IV or a port.
Some doctors may prescribe a treatment called Phesgo, which gives these two medicines by an injection under the skin. When this particular treatment is used, the chemotherapy will still be given intravenously.
Most people get Perjeta every three weeks for 18 to 25 months for metastatic breast cancer, or for up to a year for early-stage breast cancer. The first dose of Perjeta is the largest and takes about an hour to complete. After that, it takes 30 to 60 minutes to get Perjeta, which is usually given every 3 weeks in a doctor’s office.
If Phesgo is used, the treatment will take about five to ten minutes.
Perjeta side effects
Like most breast cancer medicines, Perjeta can cause side effects. The most common side effects of Perjeta are:
Because Perjeta is given with Herceptin, it’s important to know that you may experience side effects of Herceptin, such as heart problems. While research has found that adding Perjeta to Herceptin doesn’t further increase the risk of heart problems, your doctor will likely want to test your heart function before and during treatment with Perjeta, Herceptin, and chemotherapy.
Women who are pregnant or are planning to get pregnant should not take Perjeta, as it can cause embryo death and birth defects. Be sure to use effective birth control while on Perjeta.
Real patient reviews
Members of our community discuss their experiences with Perjeta 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.
“I have been on Herceptin Hylecta and IV Perjeta [HP] monotherapy. I have 6 treatments left. I had more gastrointestinal issues while on chemotherapy (TCHP) than I did on HP monotherapy (no GI issues whatsoever for the first 4 rounds of mono HP). However, since my last two HP treatments, my diarrhea has picked up. I also have upper abdominal pain, sometimes on the left and sometimes on the right. Nausea seems to be a factor on and off. I had an upper endoscopy when I was diagnosed in March; no ulcers or H pylori. Bloodwork three weeks ago was normal. My oncologist says it's unusual for me to have normal gastrointestinal function after TCHP and then suddenly develop problems in the middle of HP. I have started back on Protonix (PPI) and Pepcid.” — dlr68
“I got the small bumps on my face and terrible itching the first few weeks on H&P. Luckily, both side effects went away on their own, although the itching comes back now and then, luckily it has never been on the face because I have lightly scarred myself from scratching. Here are things I have tried with varying levels of success to quell the itch:
BioFreeze spray — sometimes very effective, but it's messy and probably not good on the face
Lidocaine in a tube, 4% I think it is, brand name is Curacaine, worked really well for a while,
Clear calamine lotion
Various roll-on 'freeze' preparations with menthol in them
Cold packs, ice, etc - freezing works well for me, but the itch starts back pretty soon after removing the ice pad
Diphenhydramine tablets — can make you sleepy
Claritin, don't know if it helps control the itching, but I started taking it daily for the runny nose & watery eyes side effect.” — olma61
Read more in our Perjeta discussion forums.
Paying for Perjeta
The cost of Perjeta 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 Perjeta.
If your doctor prescribes Perjeta and you have any problems getting it covered by insurance or don’t have insurance, you can get in touch with Access Solutions, sponsored by Genentech (the maker of Perjeta). Access Solutions can help investigate your insurance coverage benefits, appeal denied claims, and provide other assistance. You can also call Access Solutions at 1-888-249-4918.
Learn more about financial assistance and medicine cost-lowering tips.
Perjeta (pertuzumab) prescribing information. Genentech. San Francisco, CA. 2018. Available at: https://www.gene.com/download/pdf/perjeta_prescribing.pdf. (PDF)
— Last updated on July 3, 2025 at 3:52 PM
