Sustainable practice: Prescribing oral over intravenous medications

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  1. Min Na Eiiadvanced pharmacy practice1,
  2. Sarah Walpolespecialized doctor in infectious diseases2 3,
  3. Catherine Aldridgeconsultant microbiologist3
  1. 1South Tyneside and Sunderland NHS Foundation Trust, UK
  2. 2University of Newcastle, UK
  3. 3Newcastle upon Tyne Hospitals NHS Foundation Trust, UK
  1. Correspondence to M Eii minna.eii{at}

What you need to know

Oral medications can often be prescribed in place of intravenous options. Switching from intravenous to oral administration can help reduce the carbon footprint of clinical care, providing clinical, resource, and cost benefits. This article outlines the environmental benefits of oral medications over intravenous medications, and provides guidance on how to safely incorporate appropriate prescribing and intravenous to oral switches (IVOS) into clinical practice.

Why change is necessary

According to the World Health Organization, overuse of intravenous medicines when oral formulations would be more appropriate is a global phenomenon.1 Intravenous medicines are associated with higher rates of bloodstream and catheter-related infections, require more nursing resources to administer and are less comfortable . for patients than oral equivalents. They are also more expensive (both for the drugs and the equipment required for administration).2

The environmental footprint of packaging production and disposal is likely greater for all intravenous medications than for their oral forms. Based on UK emissions data, an estimate of the carbon footprint of oral and intravenous paracetamol showed that 1 g of oral paracetamol (0.003 kg CO2e) used in the perioperative period had a 68 times lower carbon footprint than 1 g intravenous paracetamol in a glass container (0.193 kg CO2e) and a 45 times lower footprint than 1 g of intravenous paracetamol in plastic packaging (0.130 kg CO2e).3 These estimates did not take into account other aspects of the drug life cycle, such as transport, storage, use, manufacture of the drugs themselves, or the environmental footprint of the equipment used to administer intravenous drugs (e.g. kits, non-sterile gloves, alcohol swabs, cannulas and cannula dressings); therefore, differences in the environmental impact of intravenous versus oral are likely underestimated. The carbon footprint of administration equipment can be significant. A quality improvement project that reduced unnecessary cannulation in an emergency department in England saved £125,000 and >24,000 kg of CO2e per year, which corresponds to more than 300 outpatient appointments for acute care.45

The environmental footprint and financial costs of intravenous medications are even greater when multidose medications require dilution with packaged diluents and specialized delivery methods such as continuous infusion pumps or in-line filters (e.g., for administration of intravenous phenytoin). Furthermore, the single-use plastics associated with intravenous drug administration contribute to the worsening pollution problem.6 From the patient’s perspective, administering drugs intravenously rather than orally is associated with an increased risk of line-related infections, permanent disability, or deformity at extravasation and/or cannula site. infection, reduced ability to mobilize independently, delayed hospital discharge and discomfort due to cannulation789

Evidence for the solution

Bioavailability research and a small number of randomized controlled trials show that switching to oral medications is often as effective as continuing with intravenous medications.1 The OVIVA study, conducted in 26 centers in Great Britain with 1,015 participants, showed indicated that for patients with complex orthopedic infections, oral antibiotics were not inferior to intravenous antibiotics.10 When intravenous therapy is recommended for six weeks, it can be safely switched to oral therapy in the first week of treatment, or in the first week after the operation if it occurred.

Accurate assessment of when to consider switching from intravenous to oral can be a challenge for clinicians, and there is significant variation in practice.11 ​​Where protocols are developed to support clinicians considering IVOS, this can lead to reductions in intravenous therapy. For example, in a prospective quasi-interventional study at a hospital in Saudi Arabia, pharmacists provided physician recommendations on whether a switch from intravenous to oral should be considered. In 60.7% of the 677 switch recommendations, a switch to intravenous medication was made, with no effect on the number of readmissions or mortality.12

What you can do

We recommend three actions that prescribers can take to improve the appropriateness of intravenous and oral prescriptions and reduce the negative environmental impact of pharmaceuticals.

1. Consider oral rather than intravenous medications when clinically indicated

Select the oral route to initiate medication, as long as the patient can tolerate oral medication in the required dose, and intravenous therapy is not expected to increase clinical benefit.

The decision to prescribe oral medications depends on patient factors such as the presence of vomiting, malabsorption, dysphagia (which affects pharmacokinetics), and the ability to adhere to the dosage (for example, if the person is confused). With antimicrobials, consider the characteristics of the infection, including the site of infection and clinical progression, as assessed by factors such as systemic features and inflammatory markers.

2. Timely assessment of intravenous medications

Assess intravenous medications for oral transition in a timely manner. For antimicrobials, this is already part of existing protocols and programs for antimicrobial stewardship.15

When switching from intravenous to oral, the same medication does not always have to be given in oral form. Particularly when a drug administered intravenously has little or no oral bioavailability, an alternative drug that has the required therapeutic properties and sufficient oral bioavailability can be considered. For example, many antibiotics, including gentamicin and cefotaxime, are not orally absorbed but can be switched to alternative agents. Some examples of drugs with high oral bioavailability are shown in Table 1.

table 1

Selected drugs with high oral bioavailability that may be considered for intravenous to oral transition121314

3. Provide education and training to support the multidisciplinary team

Health professionals can contribute to systemic changes at local, regional and national levels, prioritizing the use of oral medications over intravenous medications where appropriate. IVOS tools, such as those developed by the UK Health Security Agency,16 are guides to help doctors identify which patients are candidates for a switch from intravenous to oral antibiotics.

IVOS decision aids could potentially be adapted to guide physicians in prescribing medications other than antimicrobials and could be accessible to patients to support shared decision-making about intravenous to oral medications, as needed. Establishing intravenous-to-oral medication checklists or computer-generated reminders for the switch can support staff engagement.12 Clinical leaders can train physicians to be informed of their local IVOS protocol and its rationale. Multiprofessional education can increase physicians’ understanding of biases that can impact decision-making and the importance of effective discussion and collaboration to provide the best patient care.

A patient’s perspective

My experiences in the hospital were largely determined by the IV and the cannula in my hand. Not being able to walk around or use my arm to hold my baby after birth had a big impact. The differences between this and my experience with oral antibiotics are memorable. For this reason, I would like to switch to oral antibiotics as soon as possible, and it would also help me to know that this is better for the environment.

Education in practice

  • Does your hospital’s prescribing guidelines include information about when to prescribe oral versus intravenous medications and intravenous-to-oral switches?

  • What educational activities could you plan to encourage discussion within your team about intravenous to oral switches?

How patients were involved in the creation of this article

We spoke with a member of a sustainability group about their experiences receiving intravenous antibiotics. Based on this, we have included more details on the impact of switching from intravenous to oral from a patient’s perspective.


  • This article is part of a series providing practical actions doctors can take to support achieving net zero. Browse all articles at To pitch your article idea, visit

  • Employeeship and guarantor: ME created the article and guarantees the overall content. SW and CA reviewed, edited, and rewrote the article. A member of a local sustainability group provided a patient’s perspective on this topic. All authors approved the final draft.

  • Competing interests: SW is an associate of the Center for Sustainable Healthcare, a trustee of the Healthcare Infection Society, and was previously the Clinical Fellow to the National Medical Director at the National Institute for Health and Care Excellence. CA previously received expense reimbursements from Biomerieux for work unrelated to this article. ME is currently the Clinical Fellow to the Chief Sustainability Officer and Vice President of Sustainability at the Guild of Healthcare Pharmacists.

  • Origin and peer review: commissioned; externally peer-reviewed.

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