What might work

According to the British Medical Association, antihistamines and decongestants have been shown to be "somewhat effective" in relieving symptoms but the benefit may be small.

Antihistamines help dry up mucus in the nasal passages, making your nose slightly less runny. They can also reduce sneezing. However, the use of antihistamines to treat cold and flu systems probably won't do anything to help your overall recovery. These ingredients can also have adverse side effects, including drowsiness, headaches, and dry mouth.

Some antihistamines such as doxylamine and triprolidine can interfere with other medications. You can't use them if you're taking certain anti-depressants. They're also unsafe for people with medical conditions such as glaucoma and prostate problems.

Decongestants work by constricting blood vessels in the nose, throat and sinuses. This reduces swelling and mucus formation and can help make breathing easier.

On the flipside, oral decongestants containing pseudoephedrine or phenylephrine make some people agitated – and they may not be suitable if you have heart disease, diabetes, hyperthyroidism, or high blood pressure. Sales of pseudoephedrine are controlled because of its use in illegal drugs (it's a key ingredient in "P" manufacture).

Using a decongestant nasal spray too often or for too long can also cause "rebound" congestion. This means your blocked nose will come back when you stop taking the product.

Flu vaccines

The latest Cochrane Review on flu vaccines concludes that vaccination has "a modest effect" in lessening symptoms in healthy adults and reducing time off work. But the authors caution these results may be "optimistic" given the high number of industry-sponsored trials included in the review.

The Ministry of Health recommends everyone has a flu jab. Until 31 July 2011, vaccinations are free for people who are more at risk of getting complications from the flu: pregnant women, people aged over 65, and people aged under 65 who have underlying health conditions. Vaccinations are available from your GP.