Scopolamine side effects and how to avoid them

Common scopolamine side effects | Serious side effects | Scopolamine and seizures | Side effects timeline | Interactions | Safety measures | How to avoid side effects | How to treat side effects

Scopolamine (skoe-poe-luh-meen) is a prescription drug that treats motion sickness and prevents postoperative nausea and vomiting. It’s only available as an extended-release transdermal patch that is worn behind the ear. Whether you purchase the generic version or the brand name, Transderm Scop, it slowly releases the drug through the skin into the bloodstream for up to three days. Scopolamine is an anticholinergic, a type of drug that blocks nerve signals from the neurotransmitter acetylcholine in the part of the brain that produces nausea. 

Common side effects of scopolamine 

In clinical trials, the most common side effect of scopolamine was dry mouth, which was reported in 29% of participants and is common when taking anticholinergic drugs like scopolamine.

Other, less common side effects of scopolamine are:

• Dizziness
• Sleepiness
• Agitation
• Flushed skin
• Confusion and memory loss
• Pupil dilation
• Sore throat
• Constipation 
• Application site reactions, such as rash, burning, or itching
• Headache
• Fast heartbeat

Some of these side effects, such as confusion, flushed skin, and agitation, are signs of anticholinergic poisoning and may be due to improper administration of the patch.

Serious side effects of scopolamine 

The most serious side effect of the scopolamine patch is visual impairment. Scopolamine and other anticholinergics relax certain muscles throughout the body, including the muscle in the eye that controls the shape of the lens. As a result, the eyes can’t focus well, causing blurry vision. In clinical trials, visual impairment was reported in 5% of trial participants taking scopolamine and 3% of participants taking a harmless placebo. Scopolamine can also dilate the pupils in about 4% of patients, but this is likely due to people getting the drug on their hands when applying the patch and touching their eyes.

The most severe, long-term side effect of scopolamine is angle-closure glaucoma, but it only happens in people with an eye condition called narrow angles. Angle-closure glaucoma is a rapid buildup in eye pressure when the angle between the iris and the lens closes up. Fluid in the back of the eye cannot flow to the front of the eye where it drains, so fluid builds up quickly and can damage the retina. Without prompt treatment, narrow-angle glaucoma could result in chronic or lifelong complications, such as blindness. 

Scopolamine and seizures

Some drug information sites list seizures as a possible serious side effect of scopolamine. This is based on one study that found a substantial increase in seizures in Medicaid patients. However, a later study disproved the connection by looking at patients’ medical records. Seizures are no longer considered to be a side effect of scopolamine, but healthcare providers may be cautious about prescribing the drug to people with a history of seizures.

How soon do scopolamine side effects start?

The scopolamine patch gradually releases scopolamine through the skin. As a result, it takes about four hours for scopolamine to be detectable in the bloodstream. That’s the soonest people can expect to experience side effects if the patch is applied correctly. Most of the side effects happen early. Delayed side effects are not well-known because the patch is intended for occasional, one-time use. 

How long do scopolamine side effects last?

Scopolamine side effects may last for as long as the drug is in the bloodstream. The patch is intended only for occasional and limited use: one to three days. Once the patch is removed, the scopolamine in the bloodstream has a half-life of 9.5 hours, which is the time it takes for the drug in the body to be reduced by half. The drug will fall to undetectable levels within two days. Side effects should clear up by then.

What are the long-term side effects of scopolamine?

Side effects due to long-term use of scopolamine are unlikely. Scopolamine is only intended for occasional, short-term use for traveling or surgery. Continual use can cause withdrawal symptoms when the drug is discontinued.

Scopolamine interactions

All anticholinergic drugs can cause problems when combined with certain other types of drugs. According to the prescription drug label, these drug interactions include:

• Central nervous system (CNS) depressants: Scopolamine can increase the sedative effects and other side effects of CNS depressants, such as sleep aids, benzodiazepines, opioids, muscle relaxants, antihistamines, antidepressants, alcohol, and cannabis.

• Other anticholinergic drugs: When scopolamine is used with other anticholinergic drugs, the combination can increase the likelihood and severity of anticholinergic adverse effects, such as dry mouth, dry skin, urinary retention, blurred vision, dilated pupils, increased heart rate, and constipation.

• Oral drugs: All anticholinergic drugs can slow down the emptying of the stomach, so medicines taken orally are exposed to stomach acid for a longer time. This may significantly reduce the amount of drug absorbed into the body, making oral drugs less effective.

• Cholinergic agents: Some drugs used to treat Alzheimer’s disease, myasthenia gravis, and angle-closure glaucoma have the opposite effect of anticholinergic drugs like scopolamine, so the two types of drugs may cancel out each other’s effects.

• Glucagon: Glucagon is used to treat low blood sugar (hypoglycemia). Scopolamine should be avoided for people who need glucagon because of the risk that the digestive system will slow down too much.

Safety measures while using scopolamine 

Although the Food and Drug Administration (FDA) has not mandated any boxed warnings for scopolamine, there are a few safety measures to be aware of when using the patches.

Who should never take scopolamine?

Scopolamine is never given to people with angle-closure glaucoma, pregnant women with severe preeclampsia, and anyone who has had an allergic reaction to scopolamine.

Who should use caution with scopolamine?

Because of potential side effects or serious adverse events, healthcare professionals use caution when prescribing scopolamine to anyone with the following conditions:

• Kidney or liver disease: The risks of scopolamine for people with kidney dysfunction or liver impairment are unknown.
• Narrow angles: People with narrow angles are at a higher risk of developing angle-closure glaucoma. 
• Gastrointestinal obstruction: Scopolamine slows down the muscles in the digestive system, so someone with a gastrointestinal obstruction may experience worsening symptoms.
• Heart disease or heartbeat irregularities: Anticholinergic drugs like scopolamine speed up the heart, so caution is used in people with cardiac disease or heart arrhythmias.
• Urinary retention: Scopolamine can slow down the muscles in the bladder and worsen the symptoms of urinary retention.
• History of psychosis or schizophrenia: Scopolamine can bring on psychotic symptoms or worsen existing psychosis.
• Myasthenia gravis: Anticholinergic drugs like scopolamine might have unpredictable effects in people with myasthenia gravis.

The scopolamine patch should be removed before an MRI, or it may cause skin burns. Scopolamine should not be taken before a stomach secretion test because it will interfere with the test results.

Does scopolamine cause drug abuse or dependency?

While there is no risk of drug abuse, scopolamine can cause physical dependency if used continuously day after day. In those cases, discontinuation of scopolamine can cause withdrawal symptoms about 24 hours after the patch is taken off. Withdrawal symptoms can be severe enough to require emergency medical treatment. These symptoms include dizziness, imbalance, nausea, vomiting, headache, sweating, confusion, weakness, abdominal cramping, low blood pressure, and slow heart rate.

Can you overdose on scopolamine?

Scopolamine is administered as a transdermal patch, so overdose is unlikely but possible. It could be a result of using more than one patch or cutting the patch before applying it, as this could cause more of the drug to be absorbed. A scopolamine overdose can cause a serious condition called anticholinergic toxicity. Symptoms of overdose include dry mouth, dry skin, skin flushing, confusion, hallucinations, agitation, lethargy, sleepiness, vision changes, increased or irregular heart rate, and high blood pressure. If too much scopolamine is taken or if there are symptoms of an overdose, remove the patch immediately. Call Poison Control at 800-222-1222 or go to an emergency room. 

Is scopolamine safe to take when pregnant?

Scopolamine is not known to hurt the fetus or cause a miscarriage or congenital disabilities. However, it may cause eclamptic seizures in women with preeclampsia, so scopolamine should be used cautiously by women with preeclampsia.

Is scopolamine safe to take while breastfeeding?

Scopolamine is present in human breast milk, but there are no studies of its effects on a nursing baby. 

Is scopolamine safe for children?

The FDA has not approved scopolamine as either safe or effective in children and teens younger than 18 years of age. Keep scopolamine transdermal patches out of the reach of children.

Is scopolamine safe for seniors?

The FDA advises healthcare professionals to use caution when prescribing scopolamine to people 65 years and older. Clinical reports have shown that older adults are more likely to experience side effects, such as confusion, dizziness, hallucinations, and withdrawal symptoms, than younger adults. 

How to avoid scopolamine side effects

1. Tell your prescriber about all medical conditions.

People with certain pre-existing medical conditions are more likely to experience side effects, including serious side effects. Inform the prescriber about all past and current medical conditions, particularly:

• Glaucoma or a history of glaucoma
• Narrow angles
• History of psychosis
• Digestive system problems
• History of seizures
• Liver disease
• Kidney disease
• Pregnancy

2. Tell your prescriber about all medications being taken.

Some drug interactions can increase the risk or severity of scopolamine side effects, so tell your prescribing healthcare provider about all prescription medications, over-the-counter drugs, and dietary supplements being taken, particularly:

• Drugs that cause sleepiness
• Medications used to treat allergies, asthma, urinary incontinence, colds, bowel spasms, or motion sickness
• Antidepressants

3. Read the medication guide that comes with scopolamine and use it as directed.

The medication guide has useful guidelines for the proper application of the patch, possible side effects, and what to do if certain side effects occur. Use it only as directed—one patch at a time and only on the area of the skin where you’ve been told to put it. 

4. Do not cut the patch.

Cutting the patch will result in a higher dose absorbed through the skin. 

5. Wash your hands after applying or removing the patch.

Some of the side effects are due to people getting scopolamine on their hands while applying the patch. From there, the medicine can be spread to the eyes or mouth and cause side effects. Always wash your hands after putting the patch on and taking it off, especially if you touch the sticky side of the patch.

6. Avoid drinking alcohol.

Alcohol will worsen the sedative effects of scopolamine, including dizziness and drowsiness. It will also increase the risk of serious side effects.

How to treat side effects of scopolamine 

Many of the side effects of scopolamine are minor and temporary, but some may require medical attention. Most can be fixed by removing the patch. Call the prescriber or other healthcare professional if you experience side effects, such as:

• Changes in your mental status
• Difficulty urinating
• Abdominal pain or cramps
• Side effects that start 24 hours after removing the patch
• Blurred vision or dilated pupils

Get immediate medical care if the following symptoms occur:

• Eye pain, swelling, or vision changes in one eye
• Worsening of pre-eclampsia
• Severe side effects that occur 24 hours after removing the patch

Bottom line: Is scopolamine safe?

Scopolamine has benefits and risks, so people prescribed scopolamine patches should discuss the possible risks with the prescribing healthcare provider. When used occasionally and applied safely, scopolamine can be a powerful anti-nausea drug that’s safe to use in some people. However, be cautious about using scopolamine day after day because of the risk of severe withdrawal symptoms. Other treatment options are available if continual treatment for motion sickness is needed.