We are independent & ad-supported. We may earn a commission for purchases made through our links.
Advertiser Disclosure
Our website is an independent, advertising-supported platform. We provide our content free of charge to our readers, and to keep it that way, we rely on revenue generated through advertisements and affiliate partnerships. This means that when you click on certain links on our site and make a purchase, we may earn a commission. Learn more.
How We Make Money
We sustain our operations through affiliate commissions and advertising. If you click on an affiliate link and make a purchase, we may receive a commission from the merchant at no additional cost to you. We also display advertisements on our website, which help generate revenue to support our work and keep our content free for readers. Our editorial team operates independently of our advertising and affiliate partnerships to ensure that our content remains unbiased and focused on providing you with the best information and recommendations based on thorough research and honest evaluations. To remain transparent, we’ve provided a list of our current affiliate partners here.

Are Prescription Drug Doses Based on Patient Weight?

Mary McMahon
Updated Mar 03, 2024
Our promise to you
The Health Board is dedicated to creating trustworthy, high-quality content that always prioritizes transparency, integrity, and inclusivity above all else. Our ensure that our content creation and review process includes rigorous fact-checking, evidence-based, and continual updates to ensure accuracy and reliability.

Our Promise to you

Founded in 2002, our company has been a trusted resource for readers seeking informative and engaging content. Our dedication to quality remains unwavering—and will never change. We follow a strict editorial policy, ensuring that our content is authored by highly qualified professionals and edited by subject matter experts. This guarantees that everything we publish is objective, accurate, and trustworthy.

Over the years, we've refined our approach to cover a wide range of topics, providing readers with reliable and practical advice to enhance their knowledge and skills. That's why millions of readers turn to us each year. Join us in celebrating the joy of learning, guided by standards you can trust.

Editorial Standards

At The Health Board, we are committed to creating content that you can trust. Our editorial process is designed to ensure that every piece of content we publish is accurate, reliable, and informative.

Our team of experienced writers and editors follows a strict set of guidelines to ensure the highest quality content. We conduct thorough research, fact-check all information, and rely on credible sources to back up our claims. Our content is reviewed by subject-matter experts to ensure accuracy and clarity.

We believe in transparency and maintain editorial independence from our advertisers. Our team does not receive direct compensation from advertisers, allowing us to create unbiased content that prioritizes your interests.

All drug dosages must account for the weight of the patient, because weight plays a role in the distribution of the drug in the body's tissues. Prescription drugs are no exception to this rule, but many are designed to be suitable for patients in an “average” weight range, so that precise dosages do not need to be calculated. This is designed to make it easier for patients to use the drugs, and to make it easier for pharmacists to package them. In some cases, weight may be an important factor in the prescription, in which case the doctor will discuss it with the patient.

In the hospital, medical staffers can calculate drug doses very precisely. There are many drugs which are primarily used in the hospital, and they include dosage recommendations which usually indicate the weight of the patient in kilograms, as in “60 milligrams per kilogram.” When these drugs are prescribed, the doctor must do the math to calculate the dosage correctly, and the administering nurse or doctor may check the calculation to confirm that it is correct.

In the case of prescription drugs, asking pharmacists to formulate precise drug doses is not always practical, and sometimes patients have difficulties adhering to a drug regimen if they are obligated to deal with calculations about drug dosage. Liquid medications can be more easily adjusted for patient weight, which is why many drugs for children come in liquid form, so that a doctor can prescribe “two teaspoons daily” or “10 cubic centimeters (CCs) twice a day.” This flexibility is key when one considers that the same drug might be used to treat infections in toddlers, young children, and adolescents: obviously, an adolescent dosage would be way too high for a toddler, while a toddler dosage would be useless for an adolescent.

Pills may also be periodically adjusted to accommodate patient weights which fall outside the normal spectrum. When patients are asked to take half a pill or a pill and a half a day, it reflects a desire on the part of the doctor to achieve drug doses which are as close as possible to the recommended amount. With some drugs, a pharmacist can also create a custom compound which does allow for very precise dosage calculations, but compounding pharmacists are increasingly rare.

There are two concerns with drug doses. The first is that in an unusually slender patient, a normal dosage might be too much, increasing the side effects for the patient and potentially contributing to patient discomfort. Slender patients may also be at risk for an overdose in some cases. In larger patients, the issue is that the drug may become too diluted, necessitating a dosage which is somewhat larger than that calculated to suit patients in the normal range.

Communicating with a doctor about how a drug is working is critical, as it is possible to adjust drug doses if a drug is not working for a patient. It is also important to follow directions from a prescribing doctor very closely, to ensure that the dosage is correct. Patients who are unclear about how to administer a drug should not be afraid to ask for a demonstration from their doctors.

The Health Board is dedicated to providing accurate and trustworthy information. We carefully select reputable sources and employ a rigorous fact-checking process to maintain the highest standards. To learn more about our commitment to accuracy, read our editorial process.
Mary McMahon
By Mary McMahon

Ever since she began contributing to the site several years ago, Mary has embraced the exciting challenge of being a The Health Board researcher and writer. Mary has a liberal arts degree from Goddard College and spends her free time reading, cooking, and exploring the great outdoors.

Discussion Comments
By bythewell — On Dec 06, 2014

@Iluviaporos - I'm sure that for crucial drugs doctors are more discerning about body weight. I know I get weighed every time I go to the doctor, so they probably do take it into account to some extent when issuing medication.

This is something that people should probably keep in mind at home as well, since it's probably easy for someone who is very slender to take too many painkillers by accident.

By lluviaporos — On Dec 05, 2014

@Fa5t3r - I've never thought about this before, but I wonder if it's possible that the so-called super-bug epidemic we're currently experiencing is due in part to this. I know that antibiotic resistant bacteria often evolve through people stopping their medication before the course is over, because it allows the stronger, more resistant organisms to survive and eventually dominate.

If some patients are being given doses of antibiotic that are too low for their body-weight then the same effect might be occurring. And considering how many people are supposed to be overweight at the moment in Western countries this could be happening on a huge scale.

By Fa5t3r — On Dec 04, 2014

It is quite shocking how rarely doctors seem to take weight into account when prescribing standard medications. Ignoring a person's weight does not make it go away and it's hardly surprising that someone who might weigh more than twice the average (whether because they are tall, fat or muscular) will need twice the average dose of medication.

If they receive the wrong dose it can have serious complications for them, particularly if it's for something urgent like an infection or heart disease.

There are enough people outside the average range for this to be taken more seriously as a problem by the medical community. Frankly, I think the fact that it isn't is due to prejudice.

Mary McMahon
Mary McMahon

Ever since she began contributing to the site several years ago, Mary has embraced the exciting challenge of being a...

Learn more
The Health Board, in your inbox

Our latest articles, guides, and more, delivered daily.

The Health Board, in your inbox

Our latest articles, guides, and more, delivered daily.