By Irfan Mahmud, Pharmacist & Independent Prescriber

Side effects of GLP-1 treatments and how to reduce them

GLP-1 treatments can be very effective for weight management, but like any medication, they can cause side effects. Most are mild and settle with time, but knowing what to expect and how to manage them can make the journey far more comfortable. Here are the most common side effects and practical ways to reduce them.

1. Nausea

Nausea is the most frequently reported side effect. It often appears when starting treatment or increasing the dose.

You may notice:

• A general unsettled stomach

• Sensitivity to strong smells

• Reduced appetite

To help ease nausea:

• Eat smaller, more frequent meals

• Choose bland, gentle foods such as crackers, toast or yoghurt

• Sip water slowly rather than drinking large amounts at once

• Avoid lying down immediately after eating

2. Constipation

Slower digestion is a natural effect of GLP 1 medications, but it can lead to constipation if not managed.

You may experience:

• Less frequent bowel movements

• Bloating and discomfort

To reduce constipation:

• Increase fibre gradually through fruit, vegetables and whole grains

• Drink enough water throughout the day

• Keep moving, even gentle walking helps support digestion

3. Diarrhoea

Some people react to the medication with looser stools, especially early on.

To manage this:

• Avoid very rich or high fat foods

• Keep hydrated with water or oral rehydration drinks if needed

• Eat simple meals until symptoms settle

4. Indigestion and reflux

Changes in how the stomach empties can lead to heartburn or general discomfort after meals.

Helpful steps include:

• Eating slowly and stopping when full

• Avoiding large meals in the evening

• Reducing caffeine, spicy foods and fizzy drinks if they worsen symptoms

5. Bloating and gas

These symptoms are usually temporary and linked to slower digestion.

To ease bloating:

• Stick to smaller meals

• Limit carbonated drinks

• Consider peppermint tea, which some people find soothing

6. Tiredness or low energy

Reduced appetite can sometimes mean you are not eating enough to support your usual energy levels.

To stay energised:

• Prioritise balanced meals with protein, healthy fats and whole grains

• Avoid skipping meals completely

• Ensure you are drinking enough water

7. Headaches

Headaches may occur due to dehydration, reduced food intake or changes in blood sugar.

To help reduce them:

• Keep a steady routine of meals and snacks

• Drink water regularly

• Rest if needed and avoid excessive caffeine

8. Injection site reactions

(If using an injectable GLP 1 treatment)

Some people notice mild redness, swelling or tenderness after injecting.

To minimise this:

• Rotate injection sites each time

• Allow the medication to reach room temperature before injecting

• Use the correct technique as advised by your clinician

When to seek advice

Most side effects improve as your body adapts, but you should contact your healthcare provider if you experience:

• Persistent vomiting

• Severe abdominal pain

• Signs of dehydration

• Side effects that impact your daily routine or do not settle with time

The bottom line

GLP 1 treatments can support steady, sustainable weight loss, but managing side effects is an important part of the process. With the right habits and guidance, most people find that symptoms become easier to handle and often fade over time. Your healthcare provider can help make adjustments if needed and ensure you stay safe and comfortable throughout your treatment.

Reviewed by Irfan Mahmud, Pharmacist and Independent Prescriber (GPhC Reg. No: 2080386)

Irfan is a UK registered pharmacist and independent prescriber with expertise in weight management, primary care and lifestyle medicine. As the founder of Cuva Health, he is dedicated to providing safe, clinically approved treatments and clear, trustworthy health guidance.