When a medicine you take is causing the weight
Several commonly prescribed medicines cause weight gain in their own right — steroids, and a number used for mood, psychiatric conditions, epilepsy and diabetes among them. If your weight changed after starting something, that is worth raising with the doctor who prescribed it. What it is never worth doing is stopping on your own.
The classes most often involved
Corticosteroids, whether for asthma, an autoimmune condition, or a course for something acute. Weight gain and a change in fat distribution are well-recognised effects, and a prolonged course does more than a short one.
Several medicines used for mood and for psychiatric conditions. This is one of the better-recognised causes and one of the least often discussed with patients before starting, and the effect varies considerably between individual drugs within the same class.
Some medicines used for epilepsy, though again it varies substantially — a few in the same category have the opposite effect.
Some used for diabetes, which is a particular frustration when weight is already part of the picture.
Hormonal treatments, including some contraceptives, though the effect here is usually smaller and more variable than reputation suggests.
Beta blockers, used for blood pressure and heart conditions, modestly.
This is not a complete list and it is deliberately not specific about individual drugs. Which one you are on, and whether an alternative exists, is a question for your prescriber.
How to tell whether this is what happened
Timing is the strongest signal. Weight that began changing within weeks to a few months of starting or increasing something, without a corresponding change in how you were eating or moving.
Appetite is the second. Many of these work by increasing appetite rather than by altering metabolism directly, so people describe being hungrier rather than eating the same and gaining.
Pattern sometimes helps — steroids in particular tend to redistribute fat as well as add it.
It is also worth checking the obvious alternative before concluding: an underactive thyroid can develop at any time, and some of the conditions these medicines treat are themselves associated with weight change. Which is why this is assessed rather than assumed.
What to do, and what not to
Do not stop. This is the important line on the page. Stopping a psychiatric medicine, an anti-epileptic or a steroid abruptly can be genuinely dangerous, and the risk of doing so is considerably greater than the weight.
Do raise it with the person who prescribed it. Alternatives within the same class often exist with different effects on weight, doses can sometimes be reviewed, and the decision is theirs to make with you because they know why you are on it.
Bring specifics: when the weight started changing, how much, and whether appetite changed. That is far more useful than a general report of gaining weight.
And know that the answer may be that the medicine stays. Some are worth the weight, and the plan is then built around that reality rather than pretending it is not there.
How a weight plan changes when a medicine is contributing
The expectations change first. Progress against a medicine that is actively working the other way is slower, and measuring it against someone else's timeline is unfair to yourself.
Protein and resistance training matter more, because steroid-associated gain in particular comes with muscle loss and defending it is worth the effort.
Monitoring is closer, since several of these classes affect blood sugar and lipids as well as weight.
And nothing prescribed elsewhere is adjusted here. That is your prescriber's decision, and a weight clinic that offers to change your psychiatric or epilepsy medication is doing something it should not.
Frequently asked
Which medicines cause weight gain?
Corticosteroids, several used for mood and psychiatric conditions, some for epilepsy and some for diabetes, certain hormonal treatments and beta blockers. The effect varies considerably between individual drugs within the same class — which is why the question belongs with your prescriber.
Should I stop my medication if it is causing weight gain?
No. Stopping a psychiatric medicine, an anti-epileptic or a steroid abruptly can be genuinely dangerous, and that risk is considerably greater than the weight. Raise it with the doctor who prescribed it — alternatives within the same class often exist.
How do I know if my medicine is the cause?
Timing is the strongest signal: weight that began changing within weeks to a few months of starting or increasing something, without a change in how you were eating or moving. Appetite is the second — many work by increasing hunger rather than altering metabolism.
Can you change my medication?
No, and a weight clinic that offers to is doing something it should not. That decision belongs with the doctor who prescribed it and knows why you are on it. What we can do is assess the whole picture and build a plan around the reality.
Can I still lose weight while on these medicines?
Usually yes, though progress against a medicine working the other way is slower, and measuring yourself against someone else's timeline is unfair. Protein and resistance training matter more here, particularly with steroid-associated gain, which comes with muscle loss worth defending.