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:
When these two medicines are taken together, your body may not process your antihistamine properly.
What might happen:
The blood levels of your antihistamine may increase and cause an irregular heartbeat.
What you should do about this interaction:
Contact your healthcare professionals (e.g. doctor or pharmacist) as soon as possible about taking these two medicines together. They may already be aware of this interaction and may be monitoring you for it. It may be necessary to change you to a different antihistamine. Do not start, stop, or change the dosage of any medicine before checking with them first.
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