What's the difference between 30mg and 32.4mg tablets of phenobarbital?

Hello. I suggest you go to the emergency room or call your doctor. It sounds like you are having an allergic reaction and it needs to be seen by a doctor. Here are the symptoms too watch.

Possible side effects of phenobarbital:
All medicines may cause side effects, but many people have no, or minor side effects. Check with your doctor if any of these most COMMON side effects persist or become bothersome:

Agitated mood; clumsiness; confusion; dizziness; excessive daytime drowsiness; headache; injection site reactions; lightheadedness; low blood pressure; nausea; slow heartbeat; slowed breathing; vomiting.

Seek medical attention right away if any of these SEVERE side effects occur:
Severe allergic reactions (rash; hives; itching; difficulty breathing; tightness in the chest; swelling of the mouth, face, lips, or tongue); difficulty breathing; liver damage.

This is not a complete list of all side effects that may occur. If you have questions about side effects, contact your health care provider. Call your doctor for medical advice about side effects. To report side effects to the appropriate agency, please read the Guide to Reporting Problems to FDA.

Remember that the quicker you are treated, the safer you will be.