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Benzoic acid / hyoscyamine / methenamine / methylene blue / phenyl salicylate Side Effects

Medically reviewed by Last updated on Nov 12, 2023.

Applies to benzoic acid / hyoscyamine / methenamine / methylene blue / phenyl salicylate: oral tablet.

Serious side effects

WARNING/CAUTION: Even though it may be rare, some people may have very bad and sometimes deadly side effects when taking a drug. Tell your doctor or get medical help right away if you have any of the following signs or symptoms that may be related to a very bad side effect:

Other side effects

All drugs may cause side effects. However, many people have no side effects or only have minor side effects. Call your doctor or get medical help if any of these side effects or any other side effects bother you or do not go away:

These are not all of the side effects that may occur. If you have questions about side effects, call your doctor. Call your doctor for medical advice about side effects.

You may report side effects to the FDA at 1-800-332-1088. You may also report side effects at

For Healthcare Professionals

Applies to benzoic acid/hyoscyamine/methenamine/methylene blue/phenyl salicylate: oral tablet.


Frequency not reported: Blue to blue-green discoloration of the urine, difficult micturition, acute urinary retention[Ref]


Frequency not reported: Tachycardia, flushing[Ref]


Rare (less than 0.1%): Itching, rash, swelling[Ref]


Frequency not reported: Blue to blue-green discoloration of stools, dry mouth, nausea, vomiting[Ref]

Nervous system

Frequency not reported: Dizziness, drowsiness[Ref]


Rare (less than 0.1%): Allergic reaction (i.e., itching, rash, severe dizziness, swelling, trouble breathing)[Ref]


Rare (less than 0.1%): Dyspnea[Ref]


Frequency not reported: Blurred vision[Ref]


1. Product Information. Hyophen (benzoic acid/hyoscy/methen/mblue/phenylsal). BioComp Pharma. 2016.

Further information

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.

Some side effects may not be reported. You may report them to the FDA.