Why does Tylenol cause constipation?

​​Tylenol is a brand of paracetamol found in many medicine cabinets, but why does Tylenol cause constipation?

In this article, we will discuss what Tylenol is, whether it causes constipation, which Tylenol products will put you at a higher risk of constipation, and how you can treat it.

Does Tylenol cause constipation?

Most people who take Tylenol within the recommended dosage on the box don’t experience any side effects.

However, some research has shown that 1-10% of people who take paracetamol (the active ingredient in Tylenol) report constipation as a side effect (1).

It is important to note that this side effect is not exclusive to the tylenol brand and can happen with any paracetamol intake.

One study showed a link between constipation and paracetamol if you take more than seven tablets per week (2). This study did exclude people who had IBS, so we can’t be sure of the risk of constipation for IBS sufferers when using medications containing paracetamol.

Some Tylenol products contain additional ingredients which may also cause constipation in some people.

What is Tylenol?

Tylenol is a branded drug with the active ingredient of paracetamol. You will also be familiar with other versions of paracetamol brands such as:

• Calpol
• Panadol
• Excedrin.

Medications containing paracetamol are commonly used for mild pain relief or to bring down a fever. You can buy most of these products over the counter as they don’t require a prescription.

Are all Tylenol products as likely to give you constipation?

Some Tylenol products may be more likely to cause constipation than others. Some products contain additional ingredients which are also linked to constipation such as antihistamines or opioids.

Tylenol with added antihistamines

Tylenol is often mixed with added antihistamines such as diphenhydramine hydrochloride (aka Benadryl). This combination can help with sleeplessness because of its drowsy features, so brands often use it in night-time product ranges.

Diphenhydramine hydrochloride blocks the effects of acetylcholine, a chemical that helps muscle movement. The consequence is slower gut transit, allowing more water to be extracted from the stool, leading to constipation.

So, taking Tylenol products which include diphenhydramine hydrochloride may increase your risk of constipation.

Interestingly, chlorphenamine maleate and doxylamine succinate, used in some Tylenol products, are also antihistamines, but these products do not have constipation as a side effect! (4,5).

Tylenol with added nasal decongestants

Some Tylenol products contain nasal decongestants, such as phenylephrine hydrochloride and pseudoephedrine hydrochloride, as well as acetaminophen. This helps to treat a blocked nose typical of cold and flu.

Luckily, constipation is not included in the list of side effects for these nasal decongestants (6). This means that your overall risk of constipation is the same as when taking the standard products that contain only acetaminophen.

Tylenol with added ingredients for treating a cough

Guaifenesin is an expectorant, which means it helps to loosen mucus so you can cough it up more easily. It is often present in cough syrups. 

Dextromethorphan hydrobromide is a cough suppressor used in many over-the-counter cough syrups. Constipation is not a listed side effect of either of these substances (7). 

You can look at our handy table below to see whether your most commonly used Tylenol products contain ingredients that may increase your risk of constipation.

TYLENOL® Product	Additional active ingredients
	Diphenhydramine hydrochloride	Phenylephrine hydrochloride	Dextromethorphan hydrobromide	Guaifenesin	Chlorpheniramine maleate	Pseudoedephrine hydrochloride	Doxylamine succinate
PM extra strength liquid/caplets)	x
Sinus and headache non-drowsy caplets		x
Cold and flu severe tablets		x	x	x
Cold and flu severe day liquid		x	x	x
Nighttime severe cold and flu		x	x		x
Sinus severe daytime pain reliever caplets		x		x
Extra Strength Cold + Flu Multi-Action Day Caplets			x			x
Extra Strength Cold + Flu Multi-Action Night Caplets			x		x	x
Cold + Flu + Cough Nighttime liquid		x	x				x

Tylenol with codeine

Tylenol with codeine (Tylenol #3) is a drug which a doctor might prescribe for pain management. It has a higher risk of constipation than the standard Tylenol.

Codeine is an opioid. Opioids can slow stool movement through the gut, allowing your body more time to remove water from the stool (8). This makes it harder and dry and can make it difficult to pass.

Tylenol containing only acetaminophen

The following Tylenol products contain acetaminophen as the only active ingredient in differing doses, which means your risk of constipation is lower than some of the products mentioned above:

• Tylenol regular-strength tablets
• Tylenol rapid-release gels
• Tylenol regular-strength liquid gels
• Tylenol extra strength caplets
• Tylenol extra strength coated tablets
• Tylenol 8hr Arthritis Pain
• Tylenol extra strength dissolve packs
• Tylenol 8hr muscle aches and pain caplets
• Tylenol family suspension (2 years – adult)

How to treat constipation

You can use many methods to treat constipation caused by medications such as acetaminophen. These include making dietary changes, using a laxative, or exploring other medicines with the support of your doctor.

1. Dietary changes to treat constipation

Making sustainable lifestyle and dietary changes may help to improve constipation. These recommendations include:

• Ensuring you get 30g of fibre per day (recommended daily guidelines)
• Increasing your fluid consumption
• Increasing your exercise
• Trialling a probiotic. 

You can find more detailed information about this in our other blog posts about the benefits of probiotics for IBS and how to treat constipation.

2. Laxative use to treat constipation

Another option is to add a laxative (stool softener). Many different products are available over the counter and as prescribed medicines. Laxatives fit into two categories: 

1. Stimulant laxatives. These help the stool move through the gut more quickly.
2. Osmotic laxatives. These help water to stay in your gut so the stool is softer.

If necessary, you can get these prescribed by the GP, and they can advise you if laxatives are appropriate for your needs and which product would be most suitable.

3. Reduce your use of Tylenol where possible

If you are suffering from constipation, it is recommended that you speak to your doctor.

Suppose you have been regularly prescribed Tylenol products such as Tylenol #3 and experience constipation. Your doctor may be able to suggest other methods of pain relief which do not contain opioids, as we know they often cause constipation.

Also, if you regularly take Tylenol for stress-related headaches, there may be a benefit to employing some stress management techniques. You can find more information about this in our blog post about the effects of mental health on IBS.

Summary

Tylenol is a brand name for paracetamol or acetaminophen, which can be used to treat pain and fever. 

Constipation has been reported in some people who take Tylenol, but the risk increases when combined with other active ingredients such as codeine or diphenhydramine hydrochloride. 

You can treat constipation from Tylenol by reducing your use, making dietary changes such as increasing fibre, introducing a probiotic, or using a laxative. 

Although Tylenol products are predominantly sold as over-the-counter drugs, it is worth remembering that it still carries a risk of side effects, one of which may be constipation.

However, suppose you are still determining whether Tylenol products are the main culprit of your constipation. In that case, you can look at our post on the most common causes of constipation for other possibilities. 

Written by Annabelle Green, Registered Dietitian, reviewed by Dr Subramaniam Ramakrishnan MD