Advertising compliance for medicines and health products: the ASA and the MHRA Blue Guide explained

What you will learn from this post

• What's the difference between the ASA and the MHRA?
• What is the MHRA Blue Guide, and why does it matter for advertising compliance?
• When does each regulator get involved, and what can it do to you?

Why are there two regulators?

Advertising compliance in the UK runs on a simple model: self-regulation, backed by the law.

The advertising industry writes its own rules and funds an independent body, the ASA, to enforce them. That covers almost every ad you see, from a supermarket poster to a TikTok video.

Medicines are different because a misleading ad can hurt someone. So on top of the industry rules, there's a law. The Human Medicines Regulations 2012 set out what you can and can't say when advertising a medicine. The MHRA enforces that law on behalf of the government.

The result is two layers. The ASA deals with most problems quickly and publicly. The MHRA sits behind it with legal powers, for the cases that need them.

The ASA: the first responder

The ASA enforces two codes, both written by its sister bodies: the CAP (Committee of Advertising Practice) Code for online, social and print ads, and the BCAP Code for TV and radio. They apply to every advertiser in every sector.

For health, two parts of the CAP Code matter most:

• Section 12 covers medicines, medical devices, health-related products and beauty products. It bans ads for prescription-only medicines to the public, and says claims must be backed by evidence.
• Section 15 covers food and supplements. It controls the health claims you can make, such as "supports immunity" or "boosts energy".

The ASA can't fine anyone. Its power is visibility. It publishes every formal ruling with the advertiser's name on it, and it can follow up with sanctions: ads in search results warning about the advertiser, removal of paid search ads, and referral to Trading Standards or the MHRA.

The MHRA: the legal backstop

The MHRA licenses medicines in the UK. It also enforces the advertising part of the law.

Most of its cases end quietly, with the company agreeing to change the ad. But it has powers the ASA doesn't:

• It can require ads for new medicines to be checked before they run.
• It can order an ad to stop.
• It can prosecute. Breaking the advertising rules is a criminal offence, punishable by a fine, up to two years in prison, or both.

It also publishes its advertising investigations every month, naming the companies involved.

What is the MHRA Blue Guide?

The MHRA Blue Guide is the MHRA's official guidance on advertising medicines. It turns the legal wording into practical rules, covering:

• what counts as an ad (it's wider than most people think, including websites, social posts and press releases);
• what you can say about over-the-counter medicines to the public;
• why prescription-only medicines can't be advertised to the public at all;
• what information must appear in an ad.

The ASA's medicines rules line up with the MHRA Blue Guide, and the ASA points advertisers to it. So if your ad follows the Blue Guide, you're usually on the right side of both regulators.

The Blue Guide also matters for products that aren't medicines. If a supplement, cosmetic or wellness product claims to treat or prevent a disease, the MHRA can treat it as an unlicensed medicine. A claim can turn a product into a medicine.

The example

An online pharmacy runs an Instagram ad: "Lose a stone in 8 weeks. Weekly weight-loss jabs, delivered." It shows an injection pen. The jab is prescription-only, so the ad breaks the law and the advertising code.

Step 1: the ASA (what usually happens)

1. Someone complains to the ASA, or the ASA's own monitoring spots the ad.
2. The ASA investigates and rules against it.
3. The ad must come down, and the ruling is published with the pharmacy's name on it.
4. The pharmacy removes the ad. Case closed. No fine, no court.

Lesson: for most advertisers, the ASA is where it starts and ends.

Step 2: the MHRA (when the ASA route isn't enough)

1. The pharmacy ignores the ruling and keeps running similar ads. Or the ad is dangerous, for example telling people they don't need a medical check.
2. The ASA refers the case to the MHRA, or the MHRA picks it up directly.
3. The MHRA orders the pharmacy to stop.
4. If it still doesn't, the MHRA can prosecute. That can mean a criminal record, a fine and up to two years in prison.

Lesson: ignore the ASA and the problem becomes a legal one.

This isn't hypothetical. In July 2025 the ASA ruled against a Google ad for a "GLP-1 weekly weight loss injection". The ad never named a medicine. The words "GLP-1 injection" and a picture of an injection pen were enough to make it an ad for a prescription-only medicine.

How the ASA and MHRA work together

The two regulators don't compete for cases. They split the work:

• The ASA handles most consumer-facing ads: social posts, search ads, influencer content and clinic websites.
• The MHRA handles serious public health risks, repeat offenders and advertisers who ignore the ASA. It normally won't open a case the ASA is already dealing with.

They also share what they find. The regulators meet regularly through a liaison group, refer cases to each other and run joint campaigns. In September 2025, CAP, the MHRA and the General Pharmaceutical Council (GPhC) issued a joint warning on advertising weight-loss prescription medicines. In August 2026, the GPhC, ASA and CAP agreed to share information on pharmacy advertising.

A few other bodies fill specific gaps:

• PAGB (Proprietary Association of Great Britain) checks and approves its members' ads for over-the-counter medicines before they run.
• PMCPA (Prescription Medicines Code of Practice Authority) polices how drug companies promote medicines to doctors and pharmacists.
• GPhC can take action against pharmacies and pharmacists.

Lesson: a complaint to one regulator can easily end up with another.

Your advertising compliance checklist

• Is the product prescription-only? Don't advertise it to the public, even through images or "online consultation" offers.
• Is it a licensed medicine? Make sure every claim matches its licence. The MHRA Blue Guide explains what that means in practice.
• Is it a supplement or wellness product? Don't claim it treats or prevents illness, and check health claims against CAP Code section 15.
• Is it an over-the-counter medicine? If you're a PAGB member, get your ad approved before it runs.
• Do your influencer posts and landing pages follow the same rules as your paid ads?
• If the ASA contacts you, act on it fast. That's what keeps the MHRA out of it.

Good advertising compliance for medicines comes down to two things: follow the MHRA Blue Guide, and treat every ad, post and landing page as something the ASA could review.