MCAS treatment

There is no cure for MCAS, but treatment can help control symptoms. Treatment is usually started one step at a time, so you and your doctor can see what helps.

Antihistamines (H1 blockers)

Non-drowsy antihistamines, such as cetirizine, loratadine or fexofenadine, are usually tried first. They block histamine and can help with itching, flushing, hives and a runny nose.

A specialist may suggest a higher dose than usual. Only do this if your doctor or specialist tells you to. Read about fexofenadine and loratadine.

H2 blockers

H2 blockers, such as famotidine, block histamine in a different way. They can help with gut symptoms such as tummy pain, indigestion and feeling sick. They are often taken alongside an H1 antihistamine. Read about famotidine.

Mast cell stabilisers

Sodium cromoglicate helps stop mast cells releasing their chemicals. For gut symptoms it is taken by mouth, usually before meals. It is normally started by a specialist.

Other medicines

Montelukast blocks other chemicals that mast cells release, called leukotrienes. It may help with wheezing and other symptoms.
Steroids are sometimes used for a short time during a bad flare.
Your specialist may suggest other medicines if these do not help.

Adrenaline auto-injectors

If you have had anaphylaxis, or are at risk of it, you should be given 2 adrenaline auto-injectors to carry with you at all times. Make sure you, your family and people you live or work with know how and when to use them.

Avoiding triggers

Medicines work best alongside avoiding your triggers. Read living with MCAS for practical tips.

Common questions

Can I take more antihistamines than it says on the packet?

Only if a doctor tells you to. Specialists sometimes use higher doses for MCAS, but this should always be agreed with your doctor or specialist first.

How long does treatment take to work?

It can take several weeks to see the full effect. Your doctor may try one medicine at a time, so you can tell what helps.