In these cases, your doctor may want to change the dose, or other precautions may be necessary. The presence of other medical problems may affect the use of tamoxifen. Do not use more or less of it, and do not use it more often than your doctor ordered. The exact amount of medicine you need has been carefully worked out. Taking too much may increase the chance of side effects, while taking too little may not improve your condition.
Tamoxifen sometimes causes mild nausea and vomiting.
However, it may have to be taken for several weeks or months to be effective. Even if you begin to feel ill, do not stop using this medicine without first checking with your doctor . Ask your health care professional for ways to lessen these effects. If you vomit shortly after taking a dose of tamoxifen, check with your doctor. You will be told whether to take the dose again or to wait until the next scheduled dose.