Anticholinergic Drugs

Overview

Anticholinergic drugs are a large group of medicines that block the effects of acetylcholine. Acetylcholine is a natural chemical your nerves use to send messages around the body. Blocking it can help with some health problems, but it can also cause side effects such as dry mouth, constipation, blurred vision, confusion, or trouble passing urine. The word anticholinergic describes how a medicine works. It is not one single drug.

Anticholinergic side effects are fairly common, especially in older adults and people who take several medicines. Serious harm is much less common when medicines are used carefully and reviewed regularly.

Anyone can be affected. Older adults, people taking many medicines, and people with conditions such as dementia, glaucoma, prostate enlargement, constipation, or heart problems are more sensitive. Children can also be affected, especially if they accidentally take too much.

Symptoms

Common symptoms

• Dry mouth or dry throat
• Dry eyes or blurred vision
• Constipation
• Trouble passing urine or a weak urine stream
• Drowsiness or dizziness
• Confusion, memory problems, or trouble concentrating
• Fast heartbeat
• Reduced sweating, flushing, or feeling hot
• Dry skin

Symptoms in children

• Flushing and hot, dry skin
• Fever
• Fast heartbeat
• Dilated pupils
• Agitation, unusual sleepiness, or confusion
• Trouble passing urine
• Constipation

Symptoms in older adults

• New or worsening confusion or memory problems
• Dizziness or falls
• Severe constipation
• Trouble passing urine
• Dry mouth that makes eating or speaking difficult
• Worsening symptoms of dementia
• Greater sensitivity to heat

Causes

Main causes

• Taking one or more medicines that have anticholinergic effects
• Taking a higher dose than prescribed or an accidental overdose
• Combining prescription and over-the-counter products that add to the effect
• Individual sensitivity, especially in older adults and children
• Not having medicines reviewed regularly when several are taken

Risk factors

• Older age
• Taking many medicines, sometimes called polypharmacy
• Dementia or mild cognitive impairment
• Glaucoma
• Enlarged prostate or urinary problems
• Long-term constipation
• Heart rhythm problems
• Kidney or liver disease
• Dehydration or hot weather
• Children accidentally taking adult medicines

When to see a doctor

See a doctor urgently if:

• You cannot pass urine
• You have severe constipation with vomiting or a swollen abdomen
• You faint or feel very dizzy
• You have a fast or irregular heartbeat
• You have new or worsening confusion
• You have eye pain or sudden vision changes
• You have a high fever with hot, dry skin

Book a routine appointment if:

• Side effects are bothering you but are not severe
• You take several medicines and want a medicine review
• You notice changes in memory, balance, or bowel habits
• You are thinking about starting a new over-the-counter medicine
• You have questions about what your medicine does

Diagnosis

There is no single test for anticholinergic effects. A doctor or pharmacist will ask about your symptoms and review all your medicines, including prescription, over-the-counter, and supplement products. They may examine you and look for a pattern of side effects that could be linked to one or more medicines.

Tests that may be done

• A full medicine review, often with a pharmacist
• A physical examination
• Blood tests to check hydration, kidney function, and salt levels
• A urine test
• An ECG, or heart tracing, if you have heartbeat symptoms
• Memory or thinking checks if confusion is a concern
• An eye pressure check if you have eye symptoms

What to expect at your appointment

The review can take time, so bring all your medicines, packaging, and a list of what you take. Your clinician may ask when symptoms started and whether they change with doses. They may adjust or change a medicine, but you should not stop anything on your own.

Treatment

Treatment depends on your symptoms and the cause. The first step is usually a careful medicine review to see whether an anticholinergic medicine can be reduced, stopped, or changed to something less likely to cause the same effects. This must be done with a healthcare professional, because stopping some medicines suddenly can be harmful.

Self-care at home

• Keep an up-to-date list of all medicines and show it at every appointment
• Use one pharmacy if possible so your medicine record is together
• Ask your pharmacist before starting any over-the-counter product
• Drink enough fluids and eat fiber-rich foods to help with constipation
• Keep cool in hot weather and avoid overheating
• Use sugar-free gum or ice chips for dry mouth if it is safe for you
• Do not drive or use machinery if you feel drowsy or confused
• Do not take extra doses to make up for missed ones

Medical treatments

Your healthcare team may lower the dose, stop the medicine, or switch to a different treatment. They may also treat problems such as constipation or trouble passing urine. In serious cases, especially with overdose, emergency care may include close monitoring, cooling, fluids, heart monitoring, and medicines given by healthcare professionals to manage severe effects.

When is surgery considered?

Surgery is not a usual treatment for anticholinergic side effects. Rarely, urgent bladder or eye problems may need specialist care, but this is not common.

Living with this condition

Plan around side effects and ask for help when you need it. Keep your medicine list with you, note which medicines cause problems, and have regular reviews. If you feel dizzy or confused, avoid driving and ask someone to stay with you until you feel safe.

Lifestyle tips

• Stay hydrated, especially in warm weather
• Eat fiber-rich foods and keep moving to help your bowel habits
• Avoid getting overheated or spending long periods in hot places
• Limit alcohol, which can add to drowsiness and confusion
• Use reminders or a pill organizer if you take several medicines
• Ask a family member or carer to help with medicine reviews

Diet and exercise

A balanced diet with enough fiber and fluids can help prevent constipation. Regular gentle activity, such as walking, can support bowel health and mood. If you feel dizzy or unsteady, exercise safely and ask your clinician for advice.

Mental health and emotional wellbeing

Confusion, memory problems, and worry about medicines can affect confidence, sleep, and mood. This can be unsettling for you and your family. Talk to your clinician about any concerns. If you feel very distressed or unsafe, contact your local emergency or crisis support service.

Prevention

Not all side effects can be prevented, but risk can be lowered with regular medicine reviews, using the lowest effective dose, avoiding unnecessary anticholinergic medicines, and checking with a pharmacist before starting over-the-counter products. Never stop a prescribed medicine on your own.

Vaccines

There is no vaccine for this. Stay up to date with routine vaccines as advised by your healthcare provider.

Screening programmes

There is no specific screening test. Regular medicine reviews are the main way to spot risk, especially if you take several medicines or are older.

Complications

If left untreated

• Ongoing dry mouth and dental problems
• Long-term constipation
• Urinary retention and urinary infections
• Confusion, memory problems, and falls
• Heat illness or overheating
• Worsening thinking problems in people with dementia
• Heart rhythm problems
• Serious harm from overdose

Long-term outlook

Most people recover fully when the cause is recognized and the medicine plan is adjusted. With regular reviews and support, risk can usually be managed. Serious problems are uncommon when medicines are used carefully.

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