Severe. These medicines may interact and cause very harmful effects and are usually not taken together. Contact your healthcare professional (e.g. doctor or pharmacist) for more information.
How the interaction occurs:
Lumefantrine may slow down how quickly your liver processes metoprolol.
What might happen:
The amount of metoprolol in your blood may increase and cause side effects such as a change in the rhythm of your heart, weakness, fatigue, or dizziness.
What you should do about this interaction:
Contact your healthcare professionals (e.g. doctor or pharmacist) right away about taking these medicines together. Your doctor may want to change your medicine.Your healthcare professionals may already be aware of this interaction and may be monitoring you for it. Do not start, stop, or change the dosage of any medicine before checking with them first.Reference:1.Riamet (artemether/lumefantrine) UK summary of product characteristics. Novartis Pharmaceuticals UK Ltd. June 27, 2001.