Suffering from a cold can be annoying enough, but you may feel even worse if you are lonely, say scientists who have found that loneliness may make people report more severe symptoms.

Researchers from Rice University in the US studied about 159 people aged 18-55, nearly 60 per cent of them men.

Participants were assessed for their psychological and physical health, given cold-inducing nasal drops and quarantined for five days in hotel rooms.

The participants were monitored during and after the five-day stay.

After adjusting for demographics like gender and age, the season, depressive affect and social isolation, the results showed those who felt lonely were no more likely to get a cold than those who were not.

However those who were screened in advance for their level of loneliness and became infected - not all of the participants did - reported a greater severity of symptoms than those recorded in previous studies used as controls.

The size of the participants' social networks appeared to have no bearing on how sick they felt.

"Previous research has shown that different psycho-social factors like feeling rejected or feeling left out or not having strong social bonds with other people do make people feel worse physically, mentally and emotionally," LeRoy said.

"You can be in a crowded room and feel lonely. That perception is what seems to be important when it comes to these cold symptoms," said Angie LeRoy of Rice University.

"The effect may be the same for those under other kinds of stress, anytime you have an illness, it is a stressor, and this phenomenon would probably occur," said Chris Fagundes of Rice University.

"A predisposition, whether it is physical or mental, can be exaggerated by a subsequent stressor. In this case, the subsequent stressor is getting sick, but it could be the loss of a loved one, or getting breast cancer, which are subjects we also study," Fagundes said.

The study was published in the journal Health Psychology.