Levsin (Hyoscyamine)

Levsin (hyoscyamine) is classified as an anticholinergic-sedative. It is a combination of two drugs: belladonna alkaloids and barbiturates.

Levsin (which also goes by the brand name Anaspaz) is prescribed by a healthcare provider to relax the muscles in the bladder and intestines as well as reduce stomach acid. The medication is also used to treat irritable bowel syndrome (IBS), diverticulosis, and bladder spasms.

Blue medication pills
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How Levsin Is Taken

Levsin should be taken anywhere from 30 to 60 minutes before eating a meal.

It should never be taken at the same time as antacids (such as Tums or Rolaids) because these medications can decrease the absorption of Levsin.

Wait at least an hour after taking Levsin to take antacids.

What to Do About Missing a Dose

If you miss a dose, take it as soon as you remember. If you're due to take your next dose soon, just take that dose. Don not double up on your dose or take more than one dose at a time.

Those Who Should Not Take Levsin

Before taking Levsin, tell your healthcare provider if you have, or have ever had:

  • Asthma, emphysema, or chronic lung disease
  • Congestive heart failure
  • Down's syndrome
  • Glaucoma
  • Hypertension (high blood pressure)
  • Intestinal blockage
  • Kidney disease
  • Liver disease
  • Myasthenia gravis
  • Prostate enlargement (BPH)
  • Severe ulcerative colitis where bowel movements have stopped
  • Hyperthyroidism
  • Coronary heart disease
  • Cardiac Arrhythmias
  • Hiatal hernia with reflux esophagitis
  • Tachycardia
  • Autonomic neuropathy
  • Current fever

Levsin Side Effects

The most common side effects of Levsin include headache, nausea, constipation, rash, and vomiting.

Levsin may decrease the amount of sweat your body produces, so it is important to drink enough water while taking the drug, particularly in hot weather or while you are exercising. Levsin can increase the risk of heat prostration, fever or heat stroke.

If you have dry eyes or who wear contact lenses, you may need to increase the use of rewetting drops.

There are some serious potential side effects of Levsin, such as confusion, blurred vision, difficulty in urination, and decreased sweating. If these symptoms occur after taking Levin, contact a healthcare provider immediately.

Medication Interactions

Levsin can interact with several different classes of drugs. Your healthcare provider needs to know about all other medications and supplements (even other-the-counter drugs and vitamins) that you take.

The following medications may interact with Levsin:

  • Antacids
  • Anticoagulants
  • Antidepressants
  • Antihistamines
  • Amantadine
  • Cardiac rhythm regulators
  • Cimetidine
  • Digoxin
  • Metoclopramide
  • Monoamine oxidase inhibitors (MAOI)
  • Potassium chloride
  • Prednisone
  • Sedatives
  • Thiazide diuretics

Food Interactions

Do not drink alcohol if you are taking Levsin. Alcohol increases the sedative effect of the drug. You will also need to avoid consuming alcohol from unexpected sources, such as over-the-counter cough suppressants and cold products like Nyquil.

Levsin may cause constipation. Eating a high fiber diet and drinking plenty of water can help keep bowel function regular while taking the drug.

Safety During Pregnancy

There is not enough research to determine whether it is safe to take Levsin while you are pregnant and breastfeeding. The drug does cross the placenta and can pass into breast milk.

Although the drug's belladonna component has not been shown to cause adverse effects in pregnant women, the barbiturate portion may increase the risk of bleeding and birth defects in newborns.

Levsin should only be used during pregnancy if clearly needed. Tell your healthcare provider right away if you become pregnant while you are taking Levsin. The potential for serious side effects in an infant should be weighed against the usefulness of the medication to the mother.

Sexual Side Effects

Levsin is associated with erectile dysfunction (impotence) in men. Levsin may also suppress the production of breast milk in nursing mothers.

A Word From Verywell

Levsin is one of many medications that are used to treat IBS. It may be helpful for some people with IBS, but there are precautions to consider. People taking Levsin need to avoid alcohol and tell their healthcare provider about all medications and supplements they are taking, as some may interact with Levsin.

Tell your practitioner right away if you become pregnant while taking Levsin. While it's not clear how the drug could affect a breastfeeding infant, your healthcare provider may recommend you avoid the medication if you are pregnant or breastfeeding.

6 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. National Institutes of Health, U.S. National Library of Medicine. ED-SPAZ- Hyoscyamine Sulfate Tablet, Orally Disintegrating. DailyMed.

  2. DrugBank. Hyoscyamine.

  3. Prescriber’s Digital Reference (PDR). Levsin/SL (hyoscyamine Sulfate) Dose, Indications, Adverse Effects, Interactions.

  4. National Center for Biotechnology Information, National Institute of Diabetes and Digestive and Kidney Diseases. Hyoscyamine. NCBI Bookshelf.

  5. The American Society of Health-System Pharmacists. Hyoscyamine. U.S. National Library of Medicine - MedlinePlus Drug Information.

  6. Lippi G, Franchini M. Vitamin K in neonates: facts and mythsBlood Transfus. 2011;9(1):4–9. doi:10.2450/2010.0034-10

Additional Reading

By Amber J. Tresca
Amber J. Tresca is a freelance writer and speaker who covers digestive conditions, including IBD. She was diagnosed with ulcerative colitis at age 16.