SIDE EFFECTS: Dizziness, drowsiness, blurred vision, dry mouth, headache, trouble sleeping, constipation, flushing, dry skin, and decreased sweating may occur. If any of these effects persist or worsen, notify 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 your doctor has prescribed this medication because he or she 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 any of these unlikely but serious side effects occur: mental/mood changes (e.g., confusion, unusual excitement), fast/irregular heartbeat, difficulty urinating, decreased sexual ability, loss of coordination, slurred speech, 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 unlikely, but seek immediate medical attention if it occurs. Symptoms of a serious allergic reaction may include: 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.

PRECAUTIONS: 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. This medication should not be used if you have certain medical conditions. Before using this medicine, consult your doctor or pharmacist if you have: personal or family history of glaucoma (angle-closure type), enlarged prostate, urinary blockage problems, certain stomach/intestinal problems (e.g., slow gut, blockage, severe ulcerative colitis, infection), heart problems due to severe bleeding. Before using this medication, tell your doctor or pharmacist your medical history, especially of: overactive thyroid, other heart problems (e.g., coronary heart disease, congestive 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 medication may contain alcohol. Caution is advised if you have alcohol dependence or liver disease. Ask your doctor or pharmacist about the safe use of this product. This drug may make you dizzy or drowsy or blur your vision. Alcohol or marijuana 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. 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 effects of this drug. Hyoscyamine should be used only when clearly needed during pregnancy. Discuss the risks and benefits with your doctor. This drug passes into breast milk. Consult your doctor before breast-feeding.

DRUG INTERACTIONS: 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 anti-arrhythmic drugs (e.g., disopyramide, quinidine), anticholinergic drugs (e.g., atropine, glycopyrrolate, scopolamine), antispasmodic drugs (e.g., clidinium, dicyclomine, propantheline), certain anti-Parkinson's drugs (e.g., benztropine, trihexyphenidyl), certain azole anti-fungal drugs (ketoconazole, itraconazole), belladonna alkaloids, bisphosphonate drugs (e.g., alendronate, risedronate), corticosteroids (e.g., prednisone), digoxin (slow-dissolving tablets), MAO inhibitors (isocarboxazid, linezolid, methylene blue, moclobemide, phenelzine, procarbazine, rasagiline, safinamide, selegiline, tranylcypromine), 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, 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 product can affect the results of certain lab tests. Make sure laboratory personnel and your doctors know you use this drug.

OVERDOSE: 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 their local poison control center at 1-800-222-1222. Canada residents can call a provincial poison control center. Symptoms of overdose may include hot/dry skin, fever, unusual excitement, fast/irregular heartbeat, seizures.