Calpol Side Effects

Updated February 21, 2017

Calpol is a liquid or meltaway pain reliever intended for children that is widely available in the United Kingdom without a prescription. In its generic form, Calpol is called paracetamol, which is sold in the United States under the name acetaminophen. Calpol is commonly given to children to lower fevers, treat aches and pains that accompany influenza and alleviate pain caused by teething, sore throats and headaches. Despite its effectiveness, Calpol is not for everyone, as it presents several risks for side effects and complications in some patients.

Less Serious Side Effects

Some side effects of Calpol are not normally serious in nature, pose little discomfort and occur infrequently. Some children develop minor skin rashes after taking the drug. The meltaway or "Fast Melt" version of Calpol occasionally causes increased defecation, functioning similarly to a laxative. Unlike other over-the-counter pain relievers, Calpol typically does not cause stomach upset or gastrointestinal bleeding.

Links to Respiratory Conditions

A study conducted by Professor Richard Beasley of the Medical Research Institute of New Zealand and published in The Lancet on September 20, 2008 revealed a possible connection between the usage of paracetamol medications like Calpol and the onset of respiratory conditions. According to the study, children who took the drug during the first year of life were 46 per cent more likely to develop asthma than those who did not. Additionally, usage of paracetamol during infancy increased the risk of developing hay fever and eczema by 48 and 35 per cent, respectively.

Other Risks

In addition to the risk for minor side effects and an increased risk for developing asthma, Calpol has the potential to cause more serious medical complications. For example, repeated usage of the drug has the potential to cause liver failure or inflammation in some children. It also occasionally causes dangerous drops in blood sugar levels. Infrequently, children develop a shortage of blood platelets or thrombocytopenia from Calpol usage. Thrombocytopenia causes a number of symptoms ranging from easy bruising to bleeding within your brain, posing a serious health risk.

Drug Interactions

There are some medications which produce unwanted side effects when used in conjunction with Calpol. When combined with blood thinners like warfarin, Calpol increases your risk of experiencing uncontrollable bleeding during surgery or following an injury. Calpol also reduces the effectiveness of the anti-epileptic drug Lamotrigine, increasing the risk for a recurrence of seizures. Additionally, taking barbiturates with Calpol exacerbates inflammation or damage to your liver.


Many of the serious risks posed by Calpol are frequently caused by giving your child too much of the medication. Because of this, it is very important to follow dosage instructions carefully. If your child has an eating disorder, cystic fibrosis or HIV or is malnutrition, he is more likely to develop adverse reactions to Calpol. Additionally, you should not give your child Calpol if she has impaired kidney or liver functioning for any reason. Consult your doctor before giving Calpol to a child under two months old.

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About the Author

Faith Davies has been writing professionally since 1996, contributing to various websites. She holds an LAH insurance license in the state of Pennsylvania and has experience as a bank branch manager and lending officer. Davies graduated cum laude from the University of Pittsburgh with a Bachelor of Arts in art history.