Day 11 after quitting smokingA sore mouth, a scratchy throat

By Yevhenii, who smoked for 26 years · Updated 30 Oct 2026 · 2 min read

What's happening in your body

Two odd things show up in the first fortnight often enough that researchers have counted them. One is mouth ulcers. In a study of more than twelve hundred people at a stop smoking clinic, about two in five developed them after stopping, mostly in the first two weeks; they were usually mild, and for most of those affected they had healed within four weeks.

The other is a run of cold symptoms, such as a sore throat, sneezing and a cough. In a separate study they became more frequent in the first two weeks after stopping.

What to expect

If you have these, they tend to be at their most annoying around now. They are a common reason people decide that quitting is making them ill, or that the patch or the gum is to blame. The researchers concluded that the ulcers come from stopping smoking itself; oral products such as gum and lozenges made them slightly worse in the first week only.

The timing is on your side, because they fade while you go on not smoking. Ulcers were more common in heavier smokers, and about one person in twelve had them badly, so a rough fortnight in the mouth is not a sign that anything unusual is happening.

See a dentist or a doctor about an ulcer that has not healed after three weeks, and cold symptoms with a high temperature, shortness of breath or a cough that keeps getting worse, because those are not withdrawal.

What else you could do

For a few days, avoid very acidic, salty or spicy food and anything hard and crunchy, like toast or crisps. A soft toothbrush, cool drinks through a straw and a rinse with warm salt water all help. If you use nicotine gum or lozenges and the ulcers are worse where you keep them, ask the pharmacist about a different form rather than stopping the treatment.

Sources. McRobbie H, Hajek P, Gillison F. The relationship between smoking cessation and mouth ulcers. Nicotine Tob Res, 2004. Ussher M, West R, Steptoe A, McEwen A. Increase in common cold symptoms and mouth ulcers following smoking cessation. Tob Control, 2003. NHS, Mouth ulcers.