Name: Levsin

Levsin Precautions

Serious side effects have been reported with hyoscyamine including the following:

  • Diarrhea
  • Skin rash
  • Eye pain
  • Fast or irregular heartbeat
  • Psychosis has been reported in sensitive individuals given hyoscyamine sulfate. Tell your doctor if you notice any of these signs or symptoms:
    • confusion, disorientation, short-term memory loss, hallucinations, dysarthria, ataxia, coma, euphoria, anxiety, decreased anxiety, fatigue, insomnia, and/or agitation
  • Hyoscyamine sulfate may decrease sweating and result fever or heat stroke. Patients with a fever or those who may be exposed to elevated environmental temperatures should use caution.

If you experience any of these symptoms, call your doctor immediately:

Hyoscyamine can also cause blurred vision, drowsiness, and dizziness. Do not drive or operate heavy machinery until you know how hyoscyamine affects you.

Talk to your doctor about the risks and benefits of taking hyoscyamine if you are 65 years of age or older. Older adults should not usually take hyoscyamine because it is not as safe and may not be as effective as other medications that can be used to treat the same condition.

Do not take hyoscyamine if you:

  • are allergic to hyoscyamine or to any of its ingredients
  • have glaucoma
  • have obstructive uropathy (for example, bladder neck obstruction due to prostatic hypertrophy)
  • have obstructive disease of the gastrointestinal tract (as in achalasia, pyloroduodenal stenosis)
  • have paralytic ileus
  • intestinal issues
  • unstable cardiovascular status in acute hemorrhage
  • have severe ulcerative colitis
  • have toxic megacolon complicating ulcerative colitis
  • have myasthenia gravis

Inform MD

Before taking hyoscyamine, tell your doctor about all of your medical conditions. Especially tell your doctor if you:

  • are allergic to hyoscyamine or to any of its ingredients
  • have or had glaucoma
  • have or had heart, lung, liver, or kidney disease
  • have congestive heart failure or cardiac arrhythmias
  • have a urinary tract or intestinal obstruction
  • have an enlarged prostate
  • have ulcerative colitis (a condition which causes swelling and sores in the lining of the colon [large intestine] and rectum)
  • have myasthenia gravis.
  • have hyperthyroidism
  • have hypertension
  • are having surgery, including dental surgery. Tell your doctor or dentist that you take hyoscyamine.
  • are pregnant, plan to become pregnant, or are breast-feeding. If you become pregnant while taking hyoscyamine, call your doctor.

Tell your doctor about all the medicines you take including prescription and non-prescription medicines, vitamins, and herbal supplements.

What happens if I miss a dose?

Take the missed dose as soon as you remember. Skip the missed dose if it is almost time for your next scheduled dose. Do not take extra medicine to make up the missed dose.

What happens if I overdose?

Seek emergency medical attention or call the Poison Help line at 1-800-222-1222.

Overdose symptoms may include headache, dizziness, dry mouth, trouble swallowing, nausea, vomiting, blurred vision, hot dry skin, and feeling restless or nervous.

Levsin (hyoscyamine) side effects

Get emergency medical help if you have any of these signs of an allergic reaction: hives; difficulty breathing; swelling of your face, lips, tongue, or throat.

Stop using hyoscyamine and call your doctor at once if you have any of these serious side effects:

  • diarrhea;

  • confusion, hallucinations;

  • unusual thoughts or behavior;

  • fast, pounding, or uneven heart rate;

  • rash or flushing (warmth, redness, or tingly feeling); or

  • eye pain.

Less serious side effects may include:

  • dizziness, drowsiness, feeling nervous;

  • blurred vision, headache;

  • sleep problems (insomnia);

  • nausea, vomiting, bloating, heartburn, or constipation;

  • changes in taste;

  • problems with urination;

  • decreased sweating;

  • dry mouth; or

  • impotence, loss of interest in sex, or trouble having an orgasm.

This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.


Levsin® injection (hyoscyamine sulfate injection, USP) is a sterile solution containing 0.5 mg hyoscyamine sulfate per mL in water for injection.

Levsin® is one of the principal anticholinergic/antispasmodic components of belladonna alkaloids. The empirical formula is (C17H23NO3)2•H2SO4•2H20 and the molecular weight is 712.85. Chemically, it is benzeneacetic acid, α-(hydroxymethyl)-,8-methyl-8-azabicyclo [3.2.1.] oct-3-yl ester, [3(S)-endo]-, sulfate (2:1), dihydrate with the following structure:

The 1 mL ampuls contain as inactive ingredients: water for injection, pH is adjusted with hydrochloric acid when necessary.

Dosage and administration

The dose may be administered subcutaneously, intramuscularly, or intravenously without dilution. As with all parenteral drug products, Levsin® injection should be inspected visually for particulate matter and discoloration prior to administration whenever solution and container permit.

Gastrointestinal Disorders:

The usual adult recommended dose is 0.5 to 1 mL (0.25 to 0.5 mg). Some patients may need only a single dose; others may require administration two, three, or four times a day at four hour intervals.

Diagnostic Procedures:

The usual adult recommended dose is 0.5 to 1 mL (0.25 to 0.5 mg) administered intravenously 5 to 10 minutes prior to the diagnostic procedure.


Adults and pediatric patients over 2 years of age:

As a pre-anesthetic medication, the recommended dose is 5 µg (0.005 mg) per kg of body weight. This dose is usually given thirty to sixty minutes prior to the anticipated time of induction of anesthesia or at the time the pre-anesthetic narcotic or sedatives are administered.

Levsin® injection may be used during surgery to reduce drug-induced bradycardia. It should be administered intravenously in increments of 0.25 mL and repeated as needed.

To achieve reversal of neuromuscular blockade, the recommended dose is 0.2 mg (0.4 mL) Levsin® injection for every 1 mg neostigmine or the equivalent dose of physostigmine or pyridostigmine.

For Healthcare Professionals

Applies to hyoscyamine: compounding powder, injectable solution, oral capsule extended release, oral liquid, oral solution, oral spray, oral tablet, oral tablet chewable, oral tablet disintegrating, oral tablet extended release, sublingual tablet


Cardiovascular side effects have included tachycardia, premature ventricular depolarizations, and ventricular tachycardia.[Ref]


Gastrointestinal side effects due to the anticholinergic effects of hyoscyamine (the active ingredient contained in Levsin) have commonly included dry mouth and mucous membranes. Other reported side effects include delayed gastric emptying time, reduced gastric acid secretion, constipation, and gastroesophageal reflux.[Ref]


Hyoscyamine (the active ingredient contained in Levsin) toxicity (anticholinergic side effects) often presents as fever, tachycardia, agitation, and dry skin/mucous membranes.[Ref]


Genitourinary complications include urinary retention (due to anticholinergic effects on the urinary sphincter), which is common and dose-related, and impotence in male patients.[Ref]


Hypersensitivity reactions to hyoscyamine (the active ingredient contained in Levsin) are rare. Reactions can include urticaria, eczema, papillary hyperplasia, mucopurulent discharge, eosinophilia, pruritus, edema, hypotension, abdominal pain, tachypnea, nausea and vomiting.[Ref]

Nervous system

Nervous system side effects have included lethargy and somnolence. Higher doses may be associated with mental confusion and/or excitement. The elderly appear to be more prone to the anticholinergic effects of hyoscyamine (the active ingredient contained in Levsin) on the CNS.[Ref]


Ocular side effects due to the anticholinergic activity of hyoscyamine (the active ingredient contained in Levsin) have included inhibition of the iris sphincter muscle (possibly resulting in mydriasis), follicular conjunctivitis, and inhibition of the ciliary muscle (which can produce blurred vision). All muscarinic antagonists can precipitate glaucoma.[Ref]


Endocrine side effects have included inhibition of exocrine sweat glands. This is usually not clinically significant except when perspiration becomes a major factor in body temperature control.[Ref]

Some side effects of Levsin may not be reported. Always consult your doctor or healthcare specialist for medical advice. You may also report side effects to the FDA.

Before taking this medicine

Do not take Levsin if you are allergic to hyoscyamine, or if you have:

  • kidney disease;

  • an enlarged prostate or problems with urination;

  • intestinal blockage;

  • severe ulcerative colitis, or toxic megacolon;

  • glaucoma; or

  • myasthenia gravis.

To make sure you can safely take Levsin, tell your doctor if you have any of these other conditions:

  • heart disease, congestive heart failure;

  • a heart rhythm disorder;

  • high blood pressure;

  • overactive thyroid; or

  • hiatal hernia with GERD (gastroesophageal reflux disease).

It is not known whether hyoscyamine will harm an unborn baby. Tell your doctor if you are pregnant or plan to become pregnant while using this medication.

Hyoscyamine can pass into breast milk and may harm a nursing baby. Do not use this medication without telling your doctor if you are breast-feeding a baby.