Side Effects of Lapatinib

Common side effects of lapatinib include hand-and-foot syndrome, nausea, and diarrhea. However, studies suggest that most of these side effects are actually caused by capecitabine (a drug that is used with lapatinib). There are also potentially serious lapatinib side effects, such as severe constipation, bloody stool, and signs of an allergic reaction, that should be reported to your healthcare provider right away.

Lapatinib for Breast Cancer

Side Effects of Lapatinib: An Introduction

As with any medicine, side effects are possible with lapatinib (Tykerb^®); however, not everyone who takes the medication will experience side effects. In fact, most people tolerate it quite well. If side effects do occur, in most cases, they are minor and either require no treatment or can easily be treated by you or your healthcare provider.

(This article covers many, but not all, of the possible side effects with lapatinib. Your healthcare provider can discuss a more complete list of lapatinib side effects with you.)

Common Side Effects of Lapatinib

Lapatinib has been studied thoroughly in clinical trials, in which a group of people taking the drug have side effects documented. Lapatinib is always used in combination with capecitabine (Xeloda^®). In these studies, the most common side effects of lapatinib when used in combination with capecitabine included:

Diarrhea -- in up to 65 percent of people (see Chemotherapy-Induced Diarrhea)
Hand-and-foot syndrome (redness and tenderness of the palms and soles) -- up to 60 percent
Anemia -- up to 56 percent (see Chemotherapy and Anemia)
Nausea -- up to 44 percent
Vomiting -- up to 26 percent.

Other common side effects of lapatinib with capecitabine (occurring in 10 to 20 percent of people) included:

Mouth sores
Indigestion or heartburn
Dry skin
Arm or leg pain
Back pain
Insomnia (see Tykerb and Insomnia).

Many of these side effects are due mostly or entirely to capecitabine, not to lapatinib. In fact, nausea, hand-and-foot syndrome, and anemia are almost as common in people taking just capecitabine as in those taking both capecitabine and lapatinib (which suggests that these side effects are not caused by lapatinib).

(Side Effects of Lapatinib Continued: Page 2)