Hyoscyamine is used to treat a variety of stomach/intestinal problems such as cramps and irritable bowel syndrome. It is also used to treat other conditions such as bladder and bowel control problems, cramping pain caused by kidney stones and gallstones, and Parkinson's disease. In addition, it is used to decrease side effects of certain medications (drugs used to treat myasthenia gravis) and insecticides.

This medication works by decreasing acid production in the stomach, slowing down the natural movements of the gut, and relaxing muscles in many organs (such as the stomach, intestines, bladder, kidney, gallbladder). Hyoscyamine also lessens the amount of certain body fluids (such as saliva, sweat). This medication belongs to a class of drugs known as anticholinergics/antispasmodics.

Place this medication under the tongue and allow it to dissolve. This medication may also be swallowed whole or chewed. It may be taken with or without meals. Take it as prescribed by your doctor.

The dosage is based on your medical condition and response to treatment. Do not increase your dose or take it more often than prescribed without consulting your doctor. Adults and children 12 years and older should not take more than 1.5 milligrams in 24 hours. Children aged 2 to 12 years should not take more than 0.75 milligrams in 24 hours. Ask your doctor or pharmacist for more information.

Antacids lower the absorption of hyoscyamine. If you use antacids, take them after meals and take hyoscyamine before meals; or take antacids at least 1 hour after taking hyoscyamine.

Drink plenty of fluids while taking this medication unless your doctor directs you otherwise.

Tell your doctor if your condition lasts or gets worse.

Dizziness, drowsiness, blurred vision, dry mouth, headache, trouble sleeping, constipation, flushing, dry skin, and decreased sweating may occur. If any of these effects last or get worse, tell your doctor or pharmacist promptly.

To relieve dry mouth, suck on (sugarless) hard candy or ice chips, chew (sugarless) gum, drink water or use a saliva substitute.

Remember that this medication has been prescribed because your doctor has judged that the benefit to you is greater than the risk of side effects. Many people using this medication do not have serious side effects.

Tell your doctor right away if you have any serious side effects, including:

• mental/mood changes (such as confusion, unusual excitement)
• fast/irregular heartbeat
• difficulty urinating
• decreased sexual ability
• loss of coordination
• trouble speaking
• vomiting

Get medical help right away if you have any very serious side effects, including:

• eye pain/swelling/redness
• vision changes (such as seeing rainbows around lights at night)

A very serious allergic reaction to this drug is rare. However, get medical help right away if you notice any symptoms of a serious allergic reaction, including:

• rash
• itching/swelling (especially of the face/tongue/throat)
• severe dizziness
• trouble breathing

This is not a complete list of possible side effects. If you notice other effects not listed above, contact your doctor or pharmacist.

In the US - Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088 or at www.fda.gov/medwatch.

In Canada - Call your doctor for medical advice about side effects. You may report side effects to Health Canada at 1-866-234-2345.

Before taking hyoscyamine, tell your doctor or pharmacist if you are allergic to it; or to atropine; or if you have any other allergies. This product may contain inactive ingredients, which can cause allergic reactions or other problems. Talk to your pharmacist for more details.

Before using this medication, tell your doctor or pharmacist your medical history, especially of:

• personal or family history of glaucoma (angle-closure type)
• enlarged prostate
• urinary blockage problems
• certain stomach/intestinal problems (such as slow gut, blockage, severe ulcerative colitis, infection)
• overactive thyroid
• heart problems (such as coronary heart disease, heart failure, fast heartbeat, arrhythmias)
• high blood pressure
• kidney disease
• heartburn problems (acid reflux, hiatal hernia)
• certain nervous system problem (autonomic neuropathy)
• myasthenia gravis

Contact lens wearers may need to use wetting eye drops since this medication can cause dry eyes.

This drug may make you dizzy or drowsy or blur your vision. Alcohol or marijuana (cannabis) can make you more dizzy or drowsy. Do not drive, use machinery, or do anything that needs alertness or clear vision until you can do it safely. Limit alcoholic beverages. Talk to your doctor if you are using marijuana (cannabis).

Before having surgery, tell your doctor or dentist about all the products you use (including prescription drugs, nonprescription drugs, and herbal products).

This drug may increase the risk for heatstroke because it decreases sweating. Avoid becoming overheated in hot weather, saunas, and during exercise or other strenuous activity.

Older adults may be more sensitive to the side effects of this drug, especially confusion, drowsiness, unusual excitement, constipation, and difficulty urinating. Confusion and drowsiness can increase the risk of falling.

Children may be more sensitive to the side effects of this drug.

During pregnancy, hyoscyamine should be used only when clearly needed. Discuss the risks and benefits with your doctor.

This drug passes into breast milk. Consult your doctor before breastfeeding.

See also How to Use section.

Drug interactions may change how your medications work or increase your risk for serious side effects. This document does not contain all possible drug interactions. Keep a list of all the products you use (including prescription/nonprescription drugs and herbal products) and share it with your doctor and pharmacist. Do not start, stop, or change the dosage of any medicines without your doctor's approval.

Some products that may interact with this drug are:

• certain azole anti-fungal drugs (ketoconazole, itraconazole)
• bisphosphonate drugs (such as alendronate, risedronate)
• corticosteroids (such as prednisone)
• digoxin (slow-dissolving tablets)
• potassium tablets/capsules
• pramlintide

Tell your doctor or pharmacist if you are taking other products that cause drowsiness such as opioid pain or cough relievers (such as codeine, hydrocodone), alcohol, marijuana (cannabis), drugs for sleep or anxiety (such as alprazolam, lorazepam, zolpidem), muscle relaxants (such as carisoprodol, cyclobenzaprine), or antihistamines (such as cetirizine, diphenhydramine).

Check the labels on all your medicines (such as allergy or cough-and-cold products) because they may contain ingredients that cause drowsiness. Ask your pharmacist about using those products safely.

This medication may interfere with certain lab tests, possibly causing false test results. Make sure lab personnel and all your doctors know you use this drug.

If someone has overdosed and has serious symptoms such as passing out or trouble breathing, call 911. Otherwise, call a poison control center right away. US residents can call 1-800-222-1222. Canada residents can call 1-844-764-7669. Symptoms of overdose may include hot/dry skin, fever, unusual excitement, fast/irregular heartbeat, seizures.

Do not share this medication with others.

Management of digestive disorders may include lifestyle changes such as stress reduction programs, exercise, stopping smoking, and dietary changes to increase the effectiveness of this medicine. Talk to your doctor or pharmacist about lifestyle changes that might benefit you.

If you miss a dose, take it as soon as you remember. If it is near the time of the next dose, skip the missed dose. Take your next dose at the regular time. Do not double the dose to catch up.

Store at room temperature away from light and moisture. Do not store in the bathroom. Keep all medications away from children and pets.

Do not flush medications down the toilet or pour them into a drain unless instructed to do so. Properly discard this product when it is expired or no longer needed. Consult your pharmacist or local waste disposal company.