Medications that cause weight gain

First, the important part

Do not stop a prescribed medicine because of anything on this page. Some of the medicines most associated with weight change are treating conditions where stopping suddenly is genuinely dangerous. The point of knowing this is to be able to raise it with your prescriber, not to act alone.

It is also worth saying plainly: if a medicine has contributed to your weight, that is a pharmacological effect. It is not something you failed to counteract.

Which groups are most often involved

Medicines for mental health

Several antidepressant and antipsychotic classes are well recognised for affecting weight, and the degree varies widely between individual medicines within the same class. This matters, because it means there is often room to discuss alternatives within the same treatment goal.

Corticosteroids

Steroids taken by mouth for more than a short course increase appetite and change where the body stores fat, often noticeably around the face and abdomen. They also cause fluid retention, so some of the early change on the scale is not fat at all.

Some diabetes treatments

A few of the older glucose-lowering treatments promote weight gain as part of how they work, while others in current use are weight-neutral or reduce it. If weight is a concern alongside blood sugar, that is a reasonable thing to ask about.

Some blood pressure medicines

Certain older classes are associated with modest weight gain and with reduced exercise tolerance, which compounds the effect. Modern alternatives often are not.

Hormonal treatments

Some hormonal contraceptives and hormone therapies affect fluid balance and appetite. Effects differ substantially between preparations and between people, so individual experience here is genuinely variable rather than predictable.

Medicines for epilepsy and migraine

Several of these affect appetite in one direction or the other, and which one depends on the specific medicine rather than the condition being treated.

How to tell whether this is what is happening

The clearest signal is timing. Weight that began changing within weeks to a few months of starting or increasing a medicine, without a matching change in eating or activity, is worth raising. Fluid-related change tends to arrive faster and shows up in ankles, fingers and face.

Bring the full list, including anything bought over the counter, and the dates things started. The Consumer Medicines Information leaflet for each medicine lists recognised effects and is free to look up.

What a useful conversation sounds like

Ask whether weight change is a recognised effect of what you are taking, whether there is an alternative within the same class that is more weight-neutral, and whether the dose still matches what you need now. Those are three specific questions, and they are far easier to answer than "is my medication making me fat".