Methylphen Side Effects
Generic name: benzoic acid / hyoscyamine / methenamine / methylene blue / phenyl salicylate
Medically reviewed by Drugs.com. Last updated on Dec 12, 2020.
Note: This document contains side effect information about benzoic acid / hyoscyamine / methenamine / methylene blue / phenyl salicylate. Some of the dosage forms listed on this page may not apply to the brand name Methylphen.
For the Consumer
What are some side effects that I need to call my doctor about right away?
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:
- Signs of an allergic reaction, like rash; hives; itching; red, swollen, blistered, or peeling skin with or without fever; wheezing; tightness in the chest or throat; trouble breathing, swallowing, or talking; unusual hoarseness; or swelling of the mouth, face, lips, tongue, or throat.
- Shortness of breath.
- Trouble passing urine.
- A fast heartbeat.
- Blurred eyesight.
- Dizziness or passing out.
- A severe and sometimes deadly problem called serotonin syndrome may happen if you take this drug with certain other drugs. Call your doctor right away if you have agitation; change in balance; confusion; hallucinations; fever; fast or abnormal heartbeat; flushing; muscle twitching or stiffness; seizures; shivering or shaking; sweating a lot; severe diarrhea, upset stomach, or throwing up; or severe headache.
What are some other side effects of this drug?
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:
- Upset stomach or throwing up.
- Dry mouth.
- Change in color of urine or stool to blue or green.
- Feeling sleepy.
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 https://www.fda.gov/medwatch.
For Healthcare Professionals
Applies to benzoic acid / hyoscyamine / methenamine / methylene blue / phenyl salicylate: oral tablet
Rare (less than 0.1%): Itching, rash, swelling[Ref]
Frequency not reported: Dizziness, drowsiness[Ref]
Rare (less than 0.1%): Allergic reaction (i.e., itching, rash, severe dizziness, swelling, trouble breathing)[Ref]
Frequency not reported: Blurred vision[Ref]
More about Methylphen (benzoic acid / hyoscyamine / methenamine / methylene blue / phenyl salicylate)
- During Pregnancy
- Dosage Information
- Imprints, Shape & Color Data
- Drug Interactions
- Drug class: urinary antispasmodics
Related treatment guides
1. "Product Information. Hyophen (benzoic acid/hyoscy/methen/mblue/phenylsal)." BioComp Pharma, San Antonio, TX.
Some side effects may not be reported. You may report them to the FDA.