Adverse effects. There are side effects that are associated with taking Valtrex, but they are to be expected. Some of these side effects include nausea, headache, dizziness, and stomach pain. But these are relatively minor and common side effects. There are other side effects that a patient should let their doctor know of right away. These side effects include hallucinations, agitation, kidney problems, and mood changes. Furthermore, there are symptoms that, if the patient experiences, they should head to the emergency room. These side effects include trouble breathing, swelling of the face/throat/tongue, and severe dizziness. It is important that patients always let their doctors know about any side effects they have with their medication.
