Side Effects and Safety Concerns
Some of the more common side effects of bromelain include indigestion, nausea and diarrhea. Other side effects may include vomiting, increased heart rate, drowsiness and abnormal uterine bleeding or heavy menstruation.
Bromelain has resulted in allergic reactions and asthma symptoms, including breathing problems, tightness in the throat, skin hives, rash or itchy skin. People with allergies to pineapples should avoid bromelain. Allergic reactions may also occur in people with allergies to latex, carrot, celery, fennel, rye, wheat, papain, bee venom or grass, birch or cypress pollens.
People with peptic ulcers should not use bromelain. People with other digestive disorders should consult a qualified healthcare professional before using bromelain.
Theoretically, bromelain may increase the risk of bleeding, so people with bleeding disorders and those taking medication that can increase the risk of bleeding should only use bromelain under the supervision of their physician. It should not be taken two weeks before or after dental procedures or surgery.
The safety of bromelain in pregnant or nursing women, children or people with liver or kidney disease isn't known.
Possible Drug and Herb Interactions
People taking "blood-thinners" (anticoagulant or anti-platelet medication), such as aspirin, warfarin (Coumadin), heparin, clopidogrel (Plavix), non-steroidal anti-inflammatory medications such as ibuprofen (Motrin, Advil), naproxen (Naprosyn, Aleve) should only use bromelain under a physician's supervision. It should also be used with caution by people taking herbs and supplements that are thought to increase the risk of bleeding, such as ginkgo biloba and garlic.
Studies suggest bromelain may also increase the absorption of other medications, such as:
- amoxicillin, tetracycline and other antibiotics
- chemotherapy drugs such as 5-fluorouracil and vincristine
- "ACE inhibitor" blood pressure medications such as captopril (Capoten) and lisinopril (Zestril)
- medications that cause drowsiness, such as benzodiazepines lorazepam (Ativan) or diazepam (Valium), some antidepressants, narcotics such as codeine, and barbituates such as phenobarbitol.
Easy on the stomach 
