But it says anti-sickness drugs and hospital treatment are important in more severe cases.
The recommendations are in line with advice from NHS watchdog NICE.
Nausea and vomiting affects about 80% of pregnant women.
`Lack of understanding`
For many, it disappears within the first four months - though symptoms are not confined to the morning hours as its commonly used name suggests.
In its first guidance on the issue, the RCOG says treatment can vary around the UK and there is an occasional lack of understanding of the condition`s severity.
Its guidelines weigh up the evidence for a range of treatments - including complementary therapies - and set out specific options depending on how severe the condition is.
Anti-sickness drugs can help in the many cases, it says.
And some women may need day visits to hospitals or longer admissions for fluids and medication.
Ginger biscuits
Meanwhile, for women with mild or moderate symptoms who do not want to use drugs, acupressure (wearing a special bracelet that applies pressure) may help.
The guidance also mentions studies showing that ginger can provide some relief - including one study using ginger biscuits.
But NHS Choices warns that as ginger products are not licensed for medical use in the UK, supplements should be bought only from reputable sources.
And anyone still experiencing problems should seek medical advice.
Meanwhile, the RCOG says hypnosis is not recommended as there is not enough evidence to establish whether it is effective.
For women with more difficult symptoms, including a very severe form, known as hyperemesis gravidarum (HG), specialist treatment, including hospital admission and mental health support, should be offered, it suggests.
Caitlin Dean, who chairs the Pregnancy Sickness Support charity and had HG in three pregnancies, said: "On top of the nausea and vomiting (this could be up to 30 times a day), I had a pounding headache, incredibly heightened sense of smell and excessive saliva.
"My days would be spent lying in bed with a quiet audio-book as I couldn`t read or watch TV because it all made me sick.
"I soon became very dehydrated and was admitted to hospital at eight weeks pregnant.
"I was housebound for most of the pregnancy, which made me feel incredibly lonely."
Dr Manjeet Shehmar, lead author of the guidelines, said many women with persistent symptoms were not receiving the treatment they needed.
"Women with persistent nausea can often feel that there is a lack of understanding of their condition," she said.
"They may be unable to eat healthily, have to take time off work and feel a sense of grief or loss for what they perceive to be a normal pregnancy.
"It is therefore vital that women with this condition are given the right information and support and are made aware of the therapeutic and alternative therapies available to help them cope."
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