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Your Body Position Impacts How Quickly Pills Kick In, New Study Shows

Laying on your left-hand side may make for slower pill absorption.


Tom Hale


Tom Hale

Senior Journalist

Tom is a writer in London with a Master's degree in Journalism whose editorial work covers anything from health and the environment to technology and archaeology.

Senior Journalist

Computer generation illustration of an anatomitcal human body highlight the stomach
It's all to do with anatomical structure and asymmetry of the stomach. Image credit: Nerthuz/

Posture and body position can make a huge difference in how your body absorbs pills. In fact, certain positions could even delay the absorption of medication by over an hour, according to a new study published in the journal Physics of Fluids. 

Scientists at Johns Hopkins University used computer models based on MRI imaging to understand how drug dissolution in the human stomach is affected by a person’s posture. This simulation used a combination of fluid dynamics and biomechanics to illustrate what happens to the stomach and its liquidy contents when the body is in different positions.


The team tested four postures: standing upright, laying on the back, laying on the left side, and laying on the right.

Taking pills while lying on the right side was by far the best option, dissolving a standard medicine pill in just 10 minutes. The second was standing upright, dissolving the pill in 23 minutes, only marginally faster than lying straight back. Lagging far behind was the laying on the left side, which took up to 100 minutes to fully dissolve the pill. 

“We were very surprised that posture had such an immense effect on the dissolution rate of a pill,” Rajat Mittal, senior study author and fluid dynamics expert at Johns Hopkins, said in a statement. “I never thought about whether I was doing it right or wrong but now I’ll definitely think about it every time I take a pill.”

This is all down to the anatomical structure of the stomach, the way the contents move within it – and, basically, gravity. Most pills do not start being absorbed and working until the stomach feeds their contents into the intestine. The closer a pill lands to the last part of the stomach, the antrum, the faster it starts to dissolve. 


The antrum, however, doesn't sit at the bottom of the stomach like a plughole but instead veers off to the right in most people. So, if a person is lying on their left-hand side, the pill could have a hard job making its way to the antrum and into the intestines. On the other hand, if you lay on your right, the pill will land in the stomach right next to the antrum, making for an easy exit.

Beyond the “oh that’s interesting” factor, this study could have meaningful applications in healthcare, the researchers suggest. For physically impaired people or patients laying in hospital beds, simply changing the body position could significantly help how quickly certain medications are absorbed by the body. 

“For elderly, sedentary or bedridden people, whether they’re turning to left or to the right can have a huge impact,” Mittal explained. “Posture itself has such a huge impact it, it’s equivalent to somebody’s stomach having a very significant disfunction as far as pill dissolution is concerned,” he added.


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