For December 2025, we have asked the employment team at Tughans LLP to provide practical answers to unusual, sensitive or complex work-related queries. We call this feature “How do I handle it?”

The articles are aimed at HR professionals and other managers who may need to deal, from time to time, with the less commonplace disputes at work; issues that may, if handled incorrectly, lead to claims for discrimination, constructive dismissal or some other serious difficulty. 

Mounjaro is a popular weight loss drug which has received much recent attention in the UK. The NHS report that its side effects can include nausea, indigestion, constipation and diarrhoea, as well as potentially more serious issues. 

The starting point, like any absence, will be your absence management policy. This will usually set out the typical process you should follow with short term absences, including any trigger points which will initiate an absence management process. 
Your policy will very likely state that you will make adjustments for disabled employees, which reflects your statutory duty to make reasonable adjustments. It will be important to consider if this duty has been triggered here. 

Mounjaro is available from the NHS or privately but requires a prescription. It may have been prescribed by the employee’s GP as part of their treatment for an underlying condition which causes weight related health problems. The NHS guidance states that it may be prescribed to those with conditions including dyslipaemia, hypertension, obstructive sleep apnoea, cardiovascular disease or type 2 diabetes mellitus. These underlying conditions are all capable of meeting the statutory definition of a “disability” under the Disability Discrimination Act 1995. 

If an employee has a condition which meets this definition, which you are aware of or ought reasonably to be aware of, you will have a duty to make reasonable adjustments. If Mounjaro has been prescribed as part of the treatment for that disability, and the absence is caused by that treatment, this duty may extend to accommodating the employee’s absence to a greater extent than you would with a non-disabled employee. This could involve, for example, increasing the usual trigger points used in your absence management process. 

It is although worth remembering that in the 2015 case of Bickerstaff v Butcher, the NI tribunal accepted that the claimant’s “morbid obesity condition” constituted a disability. This followed a similar decision in the European Court of Justice that obesity itself was not a disability but would become a disability when it “entails limitation resulting in particular long-term physical, mental or psychological impairments”. This reasoning was followed by the EAT in the 2013 case of Walker v SITA Information Networking Computing, which accepted that obesity itself was not a disability, but “may make it more likely that someone is disabled”.

There is a further possibility that the employee may have suffered more severe side effects because of a disability (because of the disability itself or treatment for that disability), or they experience a side effect which is severe enough in itself to amount to a disability, though this is likely to be rare. 

However, it may be the case that the employee does not have any relevant health conditions and has been taking Mounjaro for purely “cosmetic” reasons. You do not have a duty to make adjustments for an employee who is not disabled and can manage their absence in the normal way. 

If the employee is disabled, but has been taking Mounjaro for unrelated reasons, their absence is similarly not related to their disability. Your duty to make adjustments only arises where you apply a provision, criterion or practice (i.e. maintaining suitable levels of attendance) which places a disabled person at a substantial disadvantage compared to someone who is not disabled. The adjustment must be reasonable, in the circumstances, to prevent the “PCP” from having this effect. In these circumstances, the employee is not placed at a disadvantage by the PCP compared to someone who is not disabled if the Mounjaro-related absence is taken into account, though they may be if any disability-related absence is taken into account as well. Additionally, discounting the Mounjaro-related absence is not likely to be “reasonable” because it does not address any disadvantage posed by the employee’s unrelated disability. 

In short, you should deal with this employee’s absence in the normal way, following your normal absence management process, which should include taking the individual circumstances into account. If those individual circumstances involve a condition which is, or could be, a disability, you should consider your duty to make reasonable adjustments and proceed with due caution given the higher risk of claims based on a failure to make those adjustments. If the treatment is purely cosmetic, it is likely that you can manage the absence as you normally would.