Your appetite is smaller than it used to be, and a multivitamin seems like a sensible backup. It might be helpful for some people, but a GLP-1 prescription does not automatically mean you need a multivitamin.
The better starting point is your actual routine: what you can eat, what has changed and whether you already take supplements. A health professional or dietitian can help you decide if there's a gap and which approach fits.
Look at a few ordinary days
Think about the meals and snacks you usually manage. Are there foods you used to rely on that have disappeared? Is nausea making it hard to eat regularly? Have allergies, a medical condition or a dietary preference narrowed your options?
You don't need to record every gram. A short example—“I usually have yogurt in the morning, a small sandwich at lunch and soup at night”—gives a dietitian something concrete to work with. Include drinks and any foods you avoid.
If your appetite is very low or vomiting makes eating difficult, tell your care team. A vitamin cannot replace the energy, protein, fluids and other parts of food you may be missing. Our small-appetite nourishment guide has ideas for making meals more manageable.
Why the answer isn't the same for everyone
A person eating a varied diet may have different needs from someone who avoids several food groups or has a condition affecting absorption. Age, pregnancy and medicines can matter too. A supplement can fill a specific gap, but the product should match the reason for taking it.
Research on nutrition during GLP-1 treatment is still developing. A small observational study found reduced nutrient intake in its participants; a separate analysis of a liraglutide trial did not find a significant difference in micronutrient intake between its groups. Neither tells you whether you personally need a multivitamin.
Check what you're already taking
Gather your bottles, including individual vitamins, powders and fortified drinks. Look at each serving size and the vitamins or minerals included. Some products overlap, so adding a multivitamin can increase the total amount of a nutrient more than you intended.
Formulas differ. One may contain iron while another doesn't; amounts of calcium, vitamin D or other nutrients can vary. A front label that says “complete” doesn't answer whether the product fits your particular needs.
Also check the serving directions. If the listed amounts are for two tablets but you take one, you'll receive a different amount from the figure shown. A pharmacist can help you compare products without relying on advertising.
Bring the containers or photos of the Supplement Facts panels to a pharmacist or health professional. Ask, “Is there anything here I should avoid doubling, and does this interact with my medicines?”
If you decide to take one
Ask why that product was recommended, how to use it and whether a follow-up is needed. If the tablet is hard to swallow or upsets your stomach, say so; a different form or timing may be worth discussing. Don't change the dose of a prescribed treatment on your own.
A supplement doesn't have to be forever just because you bought a large bottle. Revisit the decision if your eating pattern, medicines or health circumstances change.
Make room for food you enjoy
Practical support might be a few easy meals in the freezer, a grocery list that works for your budget or help finding foods that are comfortable to eat. Those choices can matter whether or not you take a vitamin.
The question isn't “Does everyone on a GLP-1 need one?” It's “What, if anything, would help me meet my needs?” Take that question and your current labels to the person helping you with care.