Brief Answer: no interaction Detailed Answer: there is no known interaction between methimazole and pradaxa. Pradaxa is a blood thinner that works differently than coumadin, and you husband may be more sensitive to it. The fact that he is having rectal bleeding however is obviously not normal, even if on high doses of blood thinners, and should be further evaluated, likely with a colonoscopy and possibly an endoscopy, to make sure no ulcers have developed, and rule out other gastrointestinal problems (such as polyps, cancer, etc). Pradaxa can also lower platelets, increasing even more the chances of bleeding. Keep in mind that the risk of bleeding is overall about the same between pradaxa and coumadin, however as i said they work differently, so he may have never bled with coumadin, but now with pradaxa he is more prone to bleeding. The risk of any type of bleeding with pradaxa is about 16% (compared to 18% with coumadin). My suggestion would be for him to go to the hospital for further evaluation as he should not be off any antiplatelets / anticoagulants for a long period of time given his past history of strok and heart problems

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Brief Answer: don't change meds yet Detailed Answer: don't change any medications without consulting his doctor. if he never had issues with coumadin, you can certainly bring it up to his doctor and decide if he should go back on it. certainly don't combine pradaxa / coumadin. remember that for coumadin the dose may vary and he will need regular blood check ups. Regarding the amount of gas, it is likely due to the blood in the intestines. he can take simethicone as needed for this symptom. This is over the counter. Even if the bleeding stopped, he should still be evaluated by his doctor as soon as possible. hope that helped.

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