Does valacyclovir cause constipation? (+5 factors)

In this article, we will discuss whether valacyclovir is associated with causing constipation or not. We will figure out the mechanism by which valacyclovir may or may not cause constipation in patients. Furthermore, we will look at the common side effects of valacyclovir on the gastrointestinal system.

Does valacyclovir cause constipation?

Valacyclovir may or may not constipation. Valacyclovir is an antiviral medication which is not commonly associated with causing constipation in patients. However, constipation is reported as a rare side effect of valacyclovir.

Valacyclovir is an antiviral medication used to treat various viral infections. Valacyclovir is used for herpes, shingles, and cold sores. However, valacyclovir may not completely treat herpes infection, it may help in reducing the symptoms severity and recurrence of the viral infection (1).

Constipation refers to dry and hard bowel movement which occurs three or fewer times in a week. Constipation may not always be severe if it happens once or twice, however, regularly having hard and dry faeces is an issue of concern and requires medical help (2).

If you are facing constipation or any other unusual symptoms after taking valacyclovir, then it is important to discuss this with your healthcare provider.

It is also important to keep in mind that constipation may have many other underlying causes. Therefore, consulting a healthcare provider may help you in an appropriate diagnosis and management of constipation.

What does research suggest?

According to research studies, it is stated that valacyclovir is a prodrug of acyclovir. Valacyclovir is converted to acyclovir in vivo therefore, it may possess characteristics of acyclovir.

Acyclovir may rarely cause constipation in some patients. However, this incidence is very low and studies suggest that less than 1% of patients have been reported to the FDA upon facing constipation after initiating acyclovir treatment (3).

What factors may cause valacyclovir-induced constipation?

The following may be some underlying factors for valacyclovir-induced constipation (4):

• Low fibre intake- If the patients taking valacyclovir are taking meals that are less in fibre, they may suffer from constipation. Fibre-rich foods add bulk to the stool, making it easier to pass out.

• Less hydration- Similarly, low water or fluid intake leads to dehydration which makes stools dry and hard to pass.

• Lack of physical activity- A lack of physical activity and a sedentary lifestyle, make intestinal movement difficult resulting in constipation.

• Medical or medication history- Certain medications (narcotics, anticholinergics) and underlying health conditions (inflammatory bowel disease) affect the gastrointestinal system and alter the peristaltic movements resulting in constipation.

• Psychological factors- Certain psychological factors such as stress, anxiety and depression can affect the gastrointestinal system leading to constipation.

However, it is important to note that constipation may not necessarily only be due to the valacyclovir. There may be many underlying causes for constipation as discussed, which must be ruled out for appropriate management.

What are the other common side effects of valacyclovir?

Some other common side effects of valacyclovir are (1):

• Headache
• Vomiting
• Upset stomach
• Diarrhoea
• Rash
• Fever
• Confusion
• Itching
• Blood in urine
• Yellowish skin and eyes

However, it is important to note that not all patients taking valacyclovir may experience these side effects. Some patients may face these side effects severely as compared to others depending upon their variability and response to valacyclovir.

What to do if valacyclovir causes constipation?

The first and foremost step is to consult your healthcare provider if valacyclovir is making you constipated. Valacyclovir may rarely cause constipation in some patients depending upon their variability.

Your doctor may evaluate you completely to determine the exact cause of constipation. It may be due to dietary factors or some underlying health condition which needs to be sorted to get rid of valacyclovir-induced constipation.

To treat valacyclovir-induced constipation, your doctor may provide some over-the-counter medication such as (5):

• Bulk-forming laxatives
• Lubricants
• Docusate sodium
• Osmotic laxatives
• Magnesium

If constipation is still nt cured after changing the treatment regimen, then your doctor must switch you to another antiviral medication such as acyclovir, ganciclovir, or famciclovir depending upon which suits you best.

You must also improve your lifestyle by incorporating healthy fibre-rich food, adequate hydration, physical activities, and quitting smoking and alcohol consumption to see improvement in constipation symptoms.

In my opinion

In my opinion as a pharmacist, valacyclovir may cause constipation in some individuals which is a rare onset. If you suspect any changes in your bowel after initiating valacyclovir treatment, you must consult with your doctor to rule out the appropriate cause of constipation.

If valacyclovir is the culprit, then your doctor must reduce your dosage or switch you to an appropriate antiviral medication which does not affect your bowel movement.

References